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JEE • MATHEMATICS • CROSS PRODUCT

Cross product practice · Easy

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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31 Easy
31 of 149
Application +4 | -1
If u=i+j−k,v=2i+j+k\mathbf{u}=\mathbf{i}+\mathbf{j}-\mathbf{k}, \mathbf{v}=2 \mathbf{i}+\mathbf{j}+\mathbf{k} and w=i+j+\mathbf{w}=\mathbf{i}+\mathbf{j}+ 2k2 \mathbf{k} then the magnitude of projection of u×v\mathbf{u} \times \mathbf{v} on w\mathbf{w} is given by
View answer and explanation
Correct option: D
32\sqrt{\frac{3}{2}}
Option D (32\sqrt{\frac{3}{2}}) is correct because it represents the magnitude of the projection of u×v\mathbf{u} \times \mathbf{v} on w\mathbf{w}.
32 Easy
32 of 149
Application +4 | -1
If force represented by 5i+k5 {i}+{k} is acting through the point 9i−j+2k9 {i}-{j}+2 {k}, then the moment about the point 3i+2j3 {i}+2 {j} +k+{k} is
View answer and explanation
Correct option: C
−3i−j+15k-3 {i}-{j}+15 {k}
Option C (−3i−j+15k-3 {i}-{j}+15 {k}) is correct because it is the result of the cross product between the force vector and the displacement vector from the point of application to the point about which the moment is calculated.
33 Easy
33 of 149
Application +4 | -1
The area of the triangle having vertices as i^−2j^+3k^,−2i^+3j^−k^,4i^−7j^+7k^\hat{i}-2 \hat{j}+3 \hat{k},-2 \hat{i}+3 \hat{j}-\hat{k}, 4 \hat{i}-7 \hat{j}+7 \hat{k} is:
View answer and explanation
Correct option: D
0 sq unit
Option D (0 sq unit) is correct because the vectors AB and AC are scalar multiples of each other, indicating the points are collinear and the area of the triangle is zero.
34 Easy
34 of 149
Application +4 | -1
If a=i+j−k,b=−i+2j+2k{a}={i}+{j}-{k}, {b}=-{i}+2 {j}+2 {k} and c=−i+2j−k{c}=-{i}+2 {j}-{k} then a unit vector normal to the vectors a+b{a}+{b} and b{b} −c-{c} is
View answer and explanation
Correct option: A
i{i}
Option A (i{i}) is correct because the cross product of the vectors a+b{a}+{b} and b−c{b}-{c} is parallel to the i-axis, resulting in a unit vector of i{i}.
35 Easy
35 of 149
Application +4 | -1
If the non-zero vectors a{a} and b{b} are perpendicular to each other then the solution of the equation r×a=b{r} \times {a}={b} is
View answer and explanation
Correct option: A
r=xa+1a⋅a(a×b)r=x {a}+\frac{1}{{a} \cdot {a}}({a} \times {b})
Option A (r=xa+1a⋅a(a×b)r=x {a}+\frac{{1}}{{{a} \cdot {a}}}({a} \times {b})) is correct because it satisfies the given equation r×a=b{r} \times {a}={b} and incorporates the condition that a{a} and b{b} are perpendicular.
36 Easy
36 of 149
Application +4 | -1
If the diagonals of a parallelogram are represented by the vectors 3i+j−2k3 \mathbf{i}+\mathbf{j}-2 \mathbf{k} and i+3j−4k\mathbf{i}+3 \mathbf{j}-4 \mathbf{k}, then its area in square unit is
View answer and explanation
Correct option: D
42\sqrt{42}
Option D (42\sqrt{42}) is correct because the area of the parallelogram is half the magnitude of the cross product of its diagonals.
37 Easy
37 of 149
Application +4 | -1
Unit vector perpendicular to the plane of ΔABC\Delta ABC with position vectors a, b, c of the vertices A, B, C is
View answer and explanation
Correct option: B
a×b+b×c+c×a2Δ\frac{{a \times b + b \times c + c \times a}}{{2\Delta }}
Option B (a×b+b×c+c×a2Δ\frac{{a \times b + b \times c + c \times a}}{{2\Delta }}) is correct because it represents the unit vector perpendicular to the plane of the triangle, normalized by twice the area of the triangle.
38 Easy
38 of 149
Application +4 | -1
If a⃗⊥b⃗\vec{a} \perp \vec{b}, then vector v⃗\vec{v} in terms of a⃗\vec{a} and b⃗\vec{b} satisfying the condition v⃗⋅a⃗\vec{v} \cdot \vec{a} and v⃗⋅b⃗=1\vec{v} \cdot \vec{b}=1 and [v⃗a⃗b⃗]=1\left[ {\begin{array}{cccccccccccccccccccc} {\vec v}&{\vec a}&{\vec b} \end{array}} \right] = 1 is
View answer and explanation
Correct option: A
b→∣b→∣2+a→×b→∣a→×b→∣2\frac{\overrightarrow{\mathrm{b}}}{|\overrightarrow{\mathrm{b}}|^{2}}+\frac{\overrightarrow{\mathrm{a}} \times \overrightarrow{\mathrm{b}}}{|\overrightarrow{\mathrm{a}} \times \overrightarrow{\mathrm{b}}|^{2}}
Option A (b→∥b→∥2+a→×b→∥a→×b→∥2\frac{{\overrightarrow{{\mathrm{{b}}}}}}{{\|\overrightarrow{{\mathrm{{b}}}}\|^2}} + \frac{{\overrightarrow{{\mathrm{{a}}}} \times \overrightarrow{{\mathrm{{b}}}}}}{{\|\overrightarrow{{\mathrm{{a}}}} \times \overrightarrow{{\mathrm{{b}}}}\|^2}}) is correct because it satisfies the given conditions v⃗⋅a⃗=0\vec{v} \cdot \vec{a} = 0, v⃗⋅b⃗=1\vec{v} \cdot \vec{b} = 1, and \left[ {\begin{{array}}{{*{20}{c}}} {\vec v}&{\vec a}&{\vec b} \end{{array}}} \right] = 1\left[ {\begin{{array}}{{*{20}{c}}} {\vec v}&{\vec a}&{\vec b} \end{{array}}} \right] = 1.
39 Easy
39 of 149
Application +4 | -1
If ∣a⃗∣=10,∣b⃗∣=2|\vec{a}|=10,|\vec{b}|=2 and a⃗.b⃗=12\vec{a} . \vec{b}=12, then the value of ∣a⃗×b⃗∣|\vec{a} \times \vec{b}| is
View answer and explanation
Correct option: D
16
Option D (16) is correct because it is calculated using the formula ∣a⃗×b⃗∣=∣a⃗∣∣b⃗∣sin⁡θ|\vec{a} \times \vec{b}| = |\vec{a}||\vec{b}| \sin \theta, where sin⁡θ\sin \theta is derived from a⃗.b⃗=∣a⃗∣∣b⃗∣cos⁡θ\vec{a} . \vec{b}=|\vec{a}||\vec{b}| \cos \theta.
40 Easy
40 of 149
Application +4 | -1
If r\mathbf{r} satisfies the equation r×(i+2j+k)=i−k\mathbf{r} \times(\mathbf{i}+2 \mathbf{j}+\mathbf{k})=\mathbf{i}-\mathbf{k}, then for any scalar t,rt, \mathbf{r} is equal to
View answer and explanation
Correct option: B
j+t(i+2j+k)\mathbf{j}+t(\mathbf{i}+2 \mathbf{j}+\mathbf{k})
Option B (j+t(i+2j+k)\mathbf{j}+t(\mathbf{i}+2 \mathbf{j}+\mathbf{k})) is correct because it satisfies the given equation for any scalar t.
41 Easy
41 of 149
Understanding +4 | -1
a×(b×c)\mathbf{a} \times(\mathbf{b} \times \mathbf{c}) is coplanar with
View answer and explanation
Correct option: A
b\mathbf{b} and c\mathbf{c}
Option A is correct because the vector triple product a × (b × c) lies in the plane defined by vectors b and c.
42 Easy
42 of 149
Application +4 | -1
If ∣a⃗×b⃗∣=∣a⃗⋅b⃗∣,\left| {\mathbf{\vec a} \times \mathbf{\vec b}} \right| = \left| {\mathbf{\vec a} \cdot \mathbf{\vec b}} \right|, then the angle between a⃗  and  b⃗\mathbf{\vec a}\mathrm{\;and\;}\mathbf{\vec b} is
View answer and explanation
Correct option: C
π4\frac{\mathrm{\pi }}{4}
The correct answer is C. When the magnitude of the cross product equals the magnitude of the dot product, the angle between the vectors is π4\frac{\mathrm{\pi }}{4}.
43 Easy
43 of 149
Analyzing +4 | -1
Let a⃗=2i^+7j^−k^,b^=3i^+5k^\vec{a}=2 \hat{i}+7 \hat{j}-\hat{k}, \hat{b}=3 \hat{i}+5 \hat{k} and c⃗=i^−j^+2k^\vec{c}=\hat{i}-\hat{j}+2 \hat{k}.
Let d⃗\vec{d} be a vector which is perpendicular to both a⃗\vec{a} and b⃗\vec{b}, and c⃗⋅d⃗=12\vec{c} \cdot \vec{d}=12. Then (−i^+j^−k^)⋅(c⃗×d⃗)(-\hat{i}+\hat{j}-\hat{k}) \cdot(\vec{c} \times \vec{d}) is equal to
View answer and explanation
Correct option: B
44
Option B (44) is the correct answer. The vector d⃗\vec{d} is found using the cross product of a⃗\vec{a} and b⃗\vec{b}, then scaled to satisfy the condition c⃗⋅d⃗=12\vec{c} \cdot \vec{d} = 12. Finally, the dot product (−i^+j^−k^)⋅(c⃗×d⃗)(-\hat{i}+\hat{j}-\hat{k}) \cdot (\vec{c} \times \vec{d}) is computed.
44 Easy
44 of 149
Application +4 | -1
If a⃗=2i˙^+3j˙^−k^\mathbf{\vec a} = 2\widehat {\mathbf{\dot i}} + 3\widehat {\mathbf{\dot j}} - \mathbf{\hat k}̂,   b⃗=i˙^+2 j˙^−5 k^\;\mathbf{\vec b} = \widehat {\mathbf{\dot i}} + 2\widehat {\,\mathbf{\dot j}} - 5\,\mathbf{\hat k},   c⃗=3 i˙^+5 j˙^−k^\;\mathbf{\vec c} = 3\,\widehat {\mathbf{\dot i}} + 5\widehat {\,\mathbf{\dot j}} - \mathbf{\hat k}̂, then a vector perpendicular to a⃗{\mathbf{\vec a}} and in the plane containing b⃗   and    c⃗\mathbf{\vec b}\,\;\mathrm{and\;}\,\,\mathbf{\vec c} is
View answer and explanation
Correct option: D
−17 i˙^−21 j˙^−97 k^- 17\,\widehat {\mathbf{\dot i}} - 21\,\widehat {\mathbf{\dot j}} - 97\,\mathbf{\hat k}
Option D (−17 i˙^−21 j˙^−97 k^- 17\,\widehat {\mathbf{\dot i}} - 21\,\widehat {\mathbf{\dot j}} - 97\,\mathbf{\hat k}) is correct because it represents a vector perpendicular to a⃗\vec a and lies in the plane of b⃗\vec b and c⃗\vec c.
45 Easy
45 of 149
Understanding +4 | -1
For any vectors a,b;∣a×b∣2+(a⋅b)2\mathbf{a}, \mathbf{b} ;|\mathbf{a} \times \mathbf{b}|^2+(\mathbf{a} \cdot \mathbf{b})^2 is equal to
View answer and explanation
Correct option: A
∣a∣2∣b∣2|\mathbf{a}|^2|\mathbf{b}|^2
Option A (∣a∣2∣b∣2|\mathbf{a}|^2|\mathbf{b}|^2) is correct because using the definitions of dot and cross products, the given expression simplifies to the square of the magnitudes of the vectors.
46 Easy
46 of 149
Application +4 | -1
If a=i+2j−2k,b=2i−j+k\mathbf{a}=\mathbf{i}+2 \mathbf{j}-2 \mathbf{k}, \mathbf{b}=2 \mathbf{i}-\mathbf{j}+\mathbf{k} and c=i+3j−k\mathbf{c}=\mathbf{i}+3 \mathbf{j}-\mathbf{k}, then a×(b×c)\mathbf{a} \times(\mathbf{b} \times \mathbf{c}) is equal to
View answer and explanation
Correct option: A
20i−3j+7k20 \mathrm{i}-3 \mathrm{j}+7 \mathrm{k}
Option A (20i−3j+7k20 \mathbf{i}-3 \mathbf{j}+7 \mathbf{k}) is correct because it is the result of calculating the vector triple product a×(b×c)\mathbf{a} \times (\mathbf{b} \times \mathbf{c}).
47 Easy
47 of 149
Application +4 | -1
A force F=2i^+j^−k^\mathbf{F}=2 \hat{\mathbf{i}}+\hat{\mathbf{j}}-\hat{\mathbf{k}} acts at a point AA, whose position vector is 2i^−j^2 \hat{\mathbf{i}}-\hat{\mathbf{j}}. The moment of F\mathbf{F} about the origin is
View answer and explanation
Correct option: C
i^+2j^+4k^\hat{\mathbf{i}}+2 \hat{\mathbf{j}}+4 \hat{\mathbf{k}}
Option C (i^+2j^+4k^\hat{\mathbf{i}}+2 \hat{\mathbf{j}}+4 \hat{\mathbf{k}}) is correct because the moment of a force about the origin is calculated by taking the cross product of the position vector and the force vector.
48 Easy
48 of 149
Analyzing +4 | -1
If a⃗×b⃗=c⃗×d⃗  and  a⃗×c⃗=b⃗×d⃗,\mathbf{\vec a} \times \mathbf{\vec b} = \mathbf{\vec c} \times \mathbf{\vec d}\;\mathrm{and\;}\mathbf{\vec a} \times \mathbf{\vec c} = \mathbf{\vec b} \times \mathbf{\vec d}, then
View answer and explanation
Correct option: A
(a⃗−d⃗)=λ(b⃗−c⃗)\left( {\mathbf{\vec a} - \mathbf{\vec d}} \right) = \mathrm{\lambda }\left( {\mathbf{\vec b} - \mathbf{\vec c}} \right)
Option A ((a⃗−d⃗)=λ(b⃗−c⃗)\left( {\mathbf{\vec a} - \mathbf{\vec d}} \right) = \mathrm{\lambda }\left( {\mathbf{\vec b} - \mathbf{\vec c}} \right)) is correct because it follows from the given conditions and properties of cross products.
49 Easy
49 of 149
Application +4 | -1
If a=i+j−k,b=i−j+k,c=i−j−k\mathbf{a}=\mathbf{i}+\mathbf{j}-\mathbf{k}, \mathbf{b}=\mathbf{i}-\mathbf{j}+\mathbf{k}, \mathbf{c}=\mathbf{i}-\mathbf{j}-\mathbf{k}, then a×(b×c)\mathbf{a} \times(\mathbf{b} \times \mathbf{c}) is
View answer and explanation
Correct option: B
2i−2j2 \mathrm{i}-2 \mathrm{j}
Option B (2i−2j2 \mathbf{i}-2 \mathbf{j}) is correct because it is the result of calculating the vector triple product a×(b×c)\mathbf{a} \times (\mathbf{b} \times \mathbf{c}) using the given vectors.
50 Easy
50 of 149
Application +4 | -1
If a=2i+3j−5k,b=mi+nj+12k\mathbf{a}=2 \mathbf{i}+3 \mathbf{j}-5 \mathbf{k}, \mathbf{b}=m \mathbf{i}+n \mathbf{j}+12 \mathbf{k} and a×b=0\mathbf{a} \times \mathbf{b}=0, then (m,n)=(m, n)=
View answer and explanation
Correct option: C
(−245,−365)\left(-\frac{24}{5},-\frac{36}{5}\right)
Option C ((-24/5, -36/5)) is correct because when the cross product of two vectors is zero, the vectors are parallel, allowing us to find m and n.
51 Easy
51 of 149
Analyzing +4 | -1
If Q(0,−1,−3)Q(0, - 1, - 3) is the image of the point PP in the plane 3x−y+4z=23x - y + 4z = 2 and RR is the point (3,−1,−2),(3, - 1, - 2), then the area (in sq units) of ΔPQR\Delta PQR is
View answer and explanation
Correct option: A
912\frac{{\sqrt {91} }}{2}
Option A (912\frac{{\sqrt {91} }}{{2}}) is correct because it is the area of the triangle calculated using the cross product of vectors PQ and PR.
52 Easy
52 of 149
Application +4 | -1
If a,b,c{a}, {b}, {c} be three units vectors such that a×(b×c)=(1/2)b;b{a} \times({b} \times {c})=(1 / 2) {b} ; {b} and c{c} being non-parallel then
View answer and explanation
Correct option: A
The angle between a{a} and c{c} is π/3\pi / 3
Option A (The angle between a and c is π/3\pi / 3) is correct because it is derived from the vector triple product and the condition that b and c are non-parallel.
53 Easy
53 of 149
Application +4 | -1
The area of the parallelogram whose adjacent sides are 2i^−3k^2 \hat{i}-3 \hat{k} and 4j^+2k^4 \hat{j}+2 \hat{k} is
View answer and explanation
Correct option: B
414sq4 \sqrt{14} \mathrm{sq}, units
Option B is correct because the area of the parallelogram is the magnitude of the cross product of the adjacent sides.
54 Easy
54 of 149
Application +4 | -1
If \mathbf{\vec a} = \widehat \mathbf{i} + \widehat \mathbf{j} + \mathbf{\hat k},\;\mathbf{\vec b} = \widehat \mathbf{i} + 3\widehat \mathbf{j} + 5\mathbf{\hat k}\mathbf{\vec a} = \widehat \mathbf{i} + \widehat \mathbf{j} + \mathbf{\hat k},\;\mathbf{\vec b} = \widehat \mathbf{i} + 3\widehat \mathbf{j} + 5\mathbf{\hat k} and \mathbf{\vec c} = 7\widehat \mathbf{i} + 9\widehat \mathbf{j} + 11\mathbf{\hat k}\mathbf{\vec c} = 7\widehat \mathbf{i} + 9\widehat \mathbf{j} + 11\mathbf{\hat k} then the area of parallelogram having diagonals a⃗+b⃗\mathbf{\vec a} + \mathbf{\vec b} and b⃗+c⃗\mathbf{\vec b} + \mathbf{\vec c} is
View answer and explanation
Correct option: A
46  sq  units4\sqrt 6 \;\mathrm{sq\;units}
Option A (46  sq  units4\sqrt 6 \;\mathrm{sq\;units}) is correct because it is the result of calculating the area of the parallelogram using the cross product of its diagonals.
55 Easy
55 of 149
Understanding +4 | -1
If the vectors a⃗,b⃗\mathbf{\vec a},\mathbf{\vec b} and c⃗\mathbf{\vec c} form the sides BC,CA  and  ABBC,CA\;\mathrm{and\;}AB respectively of a triangle ABCABC then
View answer and explanation
Correct option: B
a⃗×b⃗=b⃗×c⃗=c⃗×a⃗=0\mathbf{\vec a} \times \mathbf{\vec b} = \mathbf{\vec b} \times \mathbf{\vec c} = \mathbf{\vec c} \times \mathbf{\vec a} = 0
Option B is correct because the cross product of vectors representing sides of a closed triangle, taken in order, sums to zero, implying pairwise equality of cross products.
56 Easy
56 of 149
Application +4 | -1
If a⃗  ∣=10, ∣ b⃗∣=2  \mathbf{\vec a}\,\,\left| { = 10,\,} \right|\,\mathbf{\vec b}| = 2\; and   a⃗  ⋅  b⃗=12\mathrm{\;}\mathbf{\vec a}\,\, \cdot \,\,\mathbf{\vec b} = 12 then ∣ a⃗  ×  b⃗ ∣\left| {\,\mathbf{\vec a}\,\, \times \,\,\mathbf{\vec b}\,} \right| is equal to
View answer and explanation
Correct option: C
16
Option C (16) is correct because it uses the relationship between the dot product, cross product, and magnitudes of the vectors to find the magnitude of the cross product.
57 Easy
57 of 149
Application +4 | -1
Let a⃗=a1i^+a2j^+a3k^\vec{a}=a_1 \hat{i}+a_2 \hat{j}+a_3 \hat{k} and b⃗=b1i^+b2j^+b3k^\vec{b}=b_1 \hat{i}+b_2 \hat{j}+b_3 \hat{k} be two vectors such that ∣a⃗∣=1,a⃗⋅b⃗=2|\vec{a}|=1, \vec{a} \cdot \vec{b}=2 and ∣b⃗∣=4|\vec{b}|=4. If c⃗=2(a⃗×b⃗)−3b⃗\vec{c}=2(\vec{a} \times \vec{b})-3 \vec{b}, then the angle between b⃗\vec{b} and c⃗\vec{c} is equal to :
View answer and explanation
Correct option: C
cos⁡−1(−32)\cos ^{-1}\left(-\frac{\sqrt{3}}{2}\right)
The correct answer is C (cos⁡−1(−32)\cos^{-1}(-\frac{\sqrt{3}}{2})) because it is found by calculating the dot product of vectors b and c, and then using the formula for the angle between two vectors.
58 Easy
58 of 149
Application +4 | -1
A force   F⃗=2 i^+j^−k^\;\mathbf{\vec F} = 2\,\mathbf{\hat i} + \mathbf{\hat j} - \mathbf{\hat k}̂ acts at a point AA, whose position vectors is 2 i^−j^2\,\mathbf{\hat i} - \mathbf{\hat j}. The moment of F⃗\mathbf{\vec F} about the origin is
View answer and explanation
Correct option: C
i^+2 j^+4 k^\mathbf{\hat i} + 2\,\mathbf{\hat j} + 4\,\mathbf{\hat k}
Option C (i^+2 j^+4 k^\mathbf{\hat i} + 2\,\mathbf{\hat j} + 4\,\mathbf{\hat k}) is correct because it is calculated by taking the cross product of the position vector and the force vector.
59 Easy
59 of 149
Application +4 | -1
The moment of a force represented by F=i^+2j^+3k^\mathbf{F}=\hat{\mathbf{i}}+2 \hat{\mathbf{j}}+3 \hat{\mathbf{k}} about the point 2i^−j^+k^2 \hat{\mathbf{i}}-\hat{\mathbf{j}}+\hat{\mathbf{k}} is equal to
View answer and explanation
Correct option: C
−5i^−5j^+5k^-5 \hat{\mathbf{i}}-5 \hat{\mathbf{j}}+5 \hat{\mathbf{k}}
Option C (−5i^−5j^+5k^-5 \hat{\mathbf{i}}-5 \hat{\mathbf{j}}+5 \hat{\mathbf{k}}) is correct because it is the moment of the force about the given point, calculated using the cross product of the position vector and the force vector.
60 Easy
60 of 149
Analyzing +4 | -1
If a⃗×b⃗=c⃗  and  b⃗×c⃗=a⃗\mathbf{\vec a} \times \mathbf{\vec b} = \mathbf{\vec c}\mathrm{\;and\;}\mathbf{\vec b} \times \mathbf{\vec c} = \mathbf{\vec a}, then
View answer and explanation
Correct option: D
∣b⃗∣=1,  ∣c⃗∣=  ∣a⃗∣\left| {\mathbf{\vec b}\left| { = 1,\mathrm{\;}} \right|\mathbf{\vec c}\left| { = \mathrm{\;}} \right|\mathbf{\vec a}} \right|
Option D (∣b⃗∣=1,  ∣c⃗∣=  ∣a⃗∣\left| {\mathbf{\vec b}\left| { = 1,\;}\right|\mathbf{\vec c}\left| { = \;}\right|\mathbf{\vec a}} \right|) is correct because it satisfies the given cross product conditions and mutual perpendicularity of the vectors.
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