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JEE • MATHEMATICS • TRIGONOMETRIC EQUATIONS

Trigonometric equations practice · Mixed difficulty

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91 Easy
91 of 581
Application +4 | -1
If 5  cos⁡  2θ+2  cos⁡2  θ2+1=05\,\,\cos \,\,2\theta + 2\,\,{\cos ^2}\,\,\frac{\theta }{2} + 1 = 0, when (0<θ<π)(0 < \theta < \pi ), then the values of θ\theta are
View answer and explanation
Correct option: D
π3,   π−cos⁡−1(35)\frac{\pi }{3},\;\,\pi - {\cos ^{ - 1}}\left( {\frac{3}{5}} \right)
Option D is correct because the values of θ\theta are obtained by solving the given trigonometric equation within the specified interval.
92 Medium
92 of 581
Application +4 | -1
The set of all x∈(−π,π)x \in(-\pi, \pi) satisfying ∣4sin⁡x−1∣<5|4 \sin x-1| < \sqrt{5} is given by
View answer and explanation
Correct option: A
(−π10,3π10)\left(-\frac{\pi}{10}, \frac{3 \pi}{10}\right)
Option A is correct because it represents the interval where the inequality ∣4sin⁡x−1∣<5|4 \sin x - 1| < \sqrt{5} holds true within the specified range of (−π,π)(-\pi, \pi).
93 Medium
93 of 581
Analyzing +4 | -1
If ∣sin⁡xcos⁡xcos⁡xcos⁡xsin⁡xcos⁡xcos⁡xcos⁡xsin⁡x∣=0\left|\begin{array}{lll}\sin x & \cos x & \cos x \\ \cos x & \sin x & \cos x \\ \cos x & \cos x & \sin x\end{array}\right|=0, then the number of distinct real roots of this equation in the interval −π/2<x<π/2-\pi / 2 < x < \pi / 2 is
View answer and explanation
Correct option: C
2
Option C (2) is correct because solving the determinant equation leads to two distinct real roots within the given interval.
94 Medium
94 of 581
Analyzing +4 | -1
If sin⁡  (π  cot⁡  θ)=cos⁡(π  tan⁡  θ)\sin \,\,\left( {\pi \,\,\cot \,\,\theta } \right) = \cos \left( {\pi \,\,\tan \,\,\theta } \right), then
View answer and explanation
Correct option: A
cot⁡  2θ=±  14,   −34\cot \,\,2\theta = \pm \,\,\frac{1}{4},\,\; - \frac{3}{4}
Option A (cot⁡2θ=±14,−34\cot 2\theta = \pm \frac{1}{4}, -\frac{3}{4}) is correct because by using trigonometric identities and solving the equation, we find the possible values of cot⁡2θ\cot 2\theta.
95 Medium
95 of 581
Analyzing +4 | -1
If exp⁡[(sin⁡2x+sin⁡4x+sin⁡6x+…)ln⁡2]\exp ^{\left[\left(\sin ^2 x+\sin ^4 x+\sin ^6 x+\ldots\right) \ln 2\right]} satisfies the equation y2−9y+8=0y^2-9 y+8=0, then the value of cos⁡xcos⁡x+sin⁡x,0<x<π2\frac{\cos x}{\cos x+\sin x}, 0 < x < \frac{\pi}{2}, is
View answer and explanation
Correct option: B
3−12\frac{\sqrt{3}-1}{2}
Option B, 3−12\frac{{\sqrt{{3}}-1}}{{2}}, is correct because it is the simplified value of cos⁡xcos⁡x+sin⁡x\frac{{\cos x}}{{\cos x+\sin x}} when x=π3x = \frac{{\pi}}{{3}}, which is obtained from solving the given equation.
96 Easy
96 of 581
Analyzing +4 | -1
Total number of solutions of [sin⁡x]=cos⁡x[\sin x]=\cos x, where [ ] denotes the greatest integer function in [0,3π][0,3 \pi], is
View answer and explanation
Correct option: D
None of the above
Option D (None of the above) is correct because the equation [sin x] = cos x has no solution in the given interval [0, 3π].
97 Medium
97 of 581
Application +4 | -1
From the identity sin⁡3x=3sin⁡x−4sin⁡3x\sin 3 x=3 \sin x-4 \sin ^3 x it follows that if xx is real and ∣x∣<1|x| < 1, then
View answer and explanation
Correct option: B
(3x−4x3)≤1\left(3 x-4 x^3\right) \leq 1
Option B ((3x−4x3)≤1(3 x-4 x^3) \leq 1) is correct because given ∣x∣<1|x| < 1, we can substitute x=sin⁡θx = \sin \theta, and using the identity sin⁡3θ=3sin⁡θ−4sin⁡3θ\sin 3\theta = 3 \sin \theta - 4 \sin^3 \theta, we know that sin⁡3θ\sin 3\theta is always between -1 and 1, hence less than or equal to 1.
98 Medium
98 of 581
Application +4 | -1
Total number of solutions of cos⁡xcos⁡2xcos⁡3x=14\cos x \cos 2 x \cos 3 x=\frac{1}{4} in [0,π][0, \pi] is
View answer and explanation
Correct option: B
6
Option B (6) is correct because by simplifying the given trigonometric equation, we find that there are 6 solutions in the interval [0, π\pi].
99 Medium
99 of 581
Analyzing +4 | -1
The number of roots of the equation x+2  tan⁡  x=π2x + 2\,\,\tan \,\,x = \frac{\pi }{2} in the interval [0,  2  π]\left[ {0,\,\,2\;\pi } \right], is
View answer and explanation
Correct option: C
3\mathrm{3}
Option C (3) is correct because the graphs of y=tan⁡xy = \tan x and y=π4−x2y = \frac{\pi}{4} - \frac{x}{2} intersect at three points in the given interval.
100 Easy
100 of 581
Application +4 | -1
The general solution for θ\theta if sin⁡(2θ+π6)+cos⁡(θ+5π6)=2\sin \left(2 \theta+\frac{\pi}{6}\right)+\cos \left(\theta+\frac{5 \pi}{6}\right)=2 is
View answer and explanation
Correct option: A
2nπ+7π62 n \pi+\frac{7 \pi}{6}
Option A (2nπ+7π62 n \pi+\frac{{7 \pi}}{{6}}) is correct because the equation holds true only when both sine and cosine terms are equal to 1 simultaneously, leading to the general solution.
101 Easy
101 of 581
Analyzing +4 | -1
log⁡(sin⁡1∘)log⁡(sin⁡2∘)log⁡(sin⁡3∘)…log⁡(sin⁡179∘)\log \left(\sin 1^{\circ}\right) \log \left(\sin 2^{\circ}\right) \log \left(\sin 3^{\circ}\right) \ldots \log \left(\sin 179^{\circ}\right) is equal to
View answer and explanation
Correct option: B
0
Option B (0) is correct because the expression includes log⁡(sin⁡90∘)\log(\sin 90^{\circ}), which is log⁡(1)=0\log(1) = 0, making the entire product zero.
102 Easy
102 of 581
Analyzing +4 | -1
The number of values of x∈[0, 2  π]x \in \left[ {0,\,2\;\pi } \right] that satisfy cot⁡  x−cosec    x=2sin⁡  x\cot \,\,x - \mathrm{cosec\;}\,\,x = 2\sin \,\,x is
View answer and explanation
Correct option: B
2\mathrm{2}
Option D (0) is correct because the solutions obtained from solving the equation are extraneous solutions that make the original equation undefined.
103 Medium
103 of 581
Analyzing +4 | -1
The equation esin⁡x−e−sin⁡x−4=0e^{\sin x}-e^{-\sin x}-4=0 has
View answer and explanation
Correct option: A
No solution
Option A (No solution) is correct because the equation leads to sin⁡x>1\sin x > 1, which is impossible for real values of x.
104 Easy
104 of 581
Application +4 | -1
If −π≤x≤π,−π≤y≤π-\pi \leq x \leq \pi,-\pi \leq y \leq \pi and cos⁡x+cos⁡y=2\cos x+\cos y=2, then the value cos⁡(x−y)\cos (x-y) is
View answer and explanation
Correct option: C
1
Option C (1) is correct because the maximum value of cos⁡x\cos x and cos⁡y\cos y is 1, and their sum being 2 implies both must be 1, leading to x=y=0x=y=0 and cos⁡(x−y)=1\cos(x-y) = 1.
105 Medium
105 of 581
Application +4 | -1
The number of values of xx in the interval [0,   5π]\left[ {0,\;\,5\mathrm{\pi }} \right] satisfying the equation 3  sin⁡2x−7  sin⁡  x+2=03\,\,{\sin ^2}x - 7\,\,\sin \,\,x + 2 = 0 is
View answer and explanation
Correct option: C
6
Option D (6) is correct because solving the trigonometric equation and considering the interval [0, 5π\pi] yields 6 solutions.
106 Easy
106 of 581
Application +4 | -1
The number of solutions of the equation 32tan⁡2x+32sec⁡2x=81,  0≤x≤π4{32^{{{\tan }^2}x}} + {32^{{{\sec }^2}x}} = 81,\,\,0 \le x \le \frac{\pi }{4} is
View answer and explanation
Correct option: B
1
Option B (1) is correct because the equation simplifies to a form where there is only one solution for tan(x) within the given interval.
107 Easy
107 of 581
Analyzing +4 | -1
The number of solutions for the equation sin⁡  2x+cos⁡  4x=2\sin \,\,2x + \cos \,\,4x = 2 is
View answer and explanation
Correct option: A
0\mathrm{0}
Option A (0) is correct because the discriminant of the quadratic equation in sin⁡2x\sin 2x is negative, indicating no real solutions.
108 Medium
108 of 581
Application +4 | -1
If tan⁡  θ,  cos⁡  θ,  16  sin⁡  θ\tan \,\,\theta ,\,\,\cos \,\,\theta ,\,\,\frac{1}{6}\,\,\sin \,\,\theta are in G.P., then general value of θ\theta is
View answer and explanation
Correct option: A
2  n   π  ±  π3, n∈Z2\;n\;\,\pi \,\, \pm \,\,\frac{\pi }{3},\,n \in Z
Option A (2  n  π,±,π3, n∈Z2\;n\;\pi \\, \pm \\, \frac{\pi }{3},\,n \in Z) is correct because solving the geometric progression condition leads to cos⁡θ=12\cos \theta = \frac{1}{2}, which gives the general solution θ=2nπ±π3\theta = 2n\pi \pm \frac{\pi}{3}.
109 Easy
109 of 581
Application +4 | -1
If tan⁡  2x=tan⁡  2x\tan \,\,2x = \tan \,\,\frac{2}{x}, then the value of xx is
View answer and explanation
Correct option: A
nπ  ±  n2π2+164\frac{{n\mathrm{\pi }\,\, \pm \,\,\sqrt {{n^2}{\mathrm{\pi }^2} + 16} }}{4}
Option A (\frac{{n\mathrm{\pi }\\ \pm \sqrt {{{{n^2}}{\mathrm{\pi }^2} + 16} }}{4}\frac{{n\mathrm{\pi }\\ \pm \sqrt {{{{n^2}}{\mathrm{\pi }^2} + 16} }}{4}) is correct because solving the equation tan⁡2x=tan⁡2x\tan 2x = \tan \frac{2}{x} leads to this solution.
110 Medium
110 of 581
Application +4 | -1
sin⁡2π7+sin⁡4π7+sin⁡8π7\sin \frac{2 \pi}{7}+\sin \frac{4 \pi}{7}+\sin \frac{8 \pi}{7} is equal to
View answer and explanation
Correct option: A
72\frac{\sqrt{7}}{2}
Option A (72\frac{{\sqrt{{7}}}}{{2}}) is correct because the sum of sines simplifies to 72\frac{{\sqrt{{7}}}}{{2}} using trigonometric identities and sum-to-product formulas.
111 Easy
111 of 581
Application +4 | -1
If sin⁡2θ+3cos⁡θ−2=0\sin ^2 \theta+3 \cos \theta-2=0, then cos⁡3θ+sec⁡3θ=……,θ≠(2k+1)π2,k∈Z\cos ^3 \theta+\sec ^3 \theta=\ldots \ldots, \theta \neq(2 k+1) \frac{\pi}{2}, k \in Z
View answer and explanation
Correct option: A
18
Option C (y−xy-x) is correct because simplifying the given expression using trigonometric identities leads to y−xy-x.
112 Medium
112 of 581
Application +4 | -1
A value of θ\theta satisfying sin⁡5θ−sin⁡3θ+sin⁡θ=0\sin 5 \theta-\sin 3 \theta+\sin \theta=0 such that 0<θ<π20 < \theta < \frac{\pi}{2} is
View answer and explanation
Correct option: B
π6\frac{\pi}{6}
Option B (π6\frac{\pi}{6}) is the correct answer because it satisfies the given trigonometric equation within the specified range.
113 Easy
113 of 581
Analyzing +4 | -1
Total number of integral values of nn so that sin⁡x(sin⁡x+cos⁡x)=n\sin x(\sin x+\cos x)=n has atleast one solution, is
View answer and explanation
Correct option: A
2
Option A (2) is correct because the number of integral values of n for which the equation has at least one solution is 2 (0 and 1).
114 Medium
114 of 581
Application +4 | -1
If 0≤x≤π0 \leq x \leq \pi and 81sin⁡2x+81cos⁡2x=3081^{\sin ^{2} x}+81^{\cos ^{2} x}=30, then x=x=
View answer and explanation
Correct option: A
π/6\pi / 6
Option A (π/6\pi / 6) is correct because substituting x=π/6x = \pi/6 into the equation 81sin⁡2x+81cos⁡2x=3081^{\sin^2 x} + 81^{\cos^2 x} = 30 satisfies the equation.
115 Hard
115 of 581
Analyzing +4 | -1
If the expression sin⁡  x2  +  cos⁡  x2−  i  tan⁡  x1+2 i  sin⁡  x2\frac{{\sin \,\,\frac{x}{2}\,\, + \,\,\cos \,\,\frac{x}{2} - \,\,i\,\,\tan \,\,x}}{{1 + 2\,i\,\,\sin \,\,\frac{x}{2}}} is real, then x is equal to
View answer and explanation
Correct option: C
2n  π+2tan⁡−1k2n\;\pi + 2{\tan ^{ - 1}}k, where k∈(1,2),  n∈Zk \in \left( {1,2} \right),\,\,n \in Z
Option C (2n;π+2tan⁡−1k2n\\;\pi + 2{\tan ^{ - 1}}k, where k∈(1,2),,n∈Zk \in \left( {1,2} \right),\\,n \in Z) is correct because it represents the solution for x when the given expression is real, derived by setting the imaginary part to zero.
116 Easy
116 of 581
Understanding +4 | -1
Consider the following statements.

I. Equal numbers may be added to (or subtracted from) both sides of an inequality.

II. When both sides are multiplied (or divided) by a negative number, then the inequality is reversed.

Choose the correct option.
View answer and explanation
Correct option: C
Both I and II are true
Option C (Both I and II are true) is correct because these are fundamental rules for manipulating inequalities.
117 Easy
117 of 581
Application +4 | -1
If the equation sin⁡2  θ−cos⁡  θ=14{\sin ^2}\,\,\mathrm{\theta } - \cos \,\,\mathrm{\theta } = \frac{1}{4}, then the value of θ\mathrm{\theta } lying in the interval 0  ≤  θ  ≤  2π0\,\, \le \,\,\mathrm{\theta }\,\, \le \,\,2\mathrm{\pi } is
View answer and explanation
Correct option: A
π3,  5 π3\frac{\mathrm{\pi }}{3},\,\,\frac{{5\,\mathrm{\pi }}}{3}
Option A (π3, 5 π3\frac{\mathrm{\pi }}{3},\,\frac{{5\,\mathrm{\pi }}}{3}) is correct because these values of θ\theta satisfy the given equation sin⁡2 θ−cos⁡ θ=14{\sin ^2}\,\mathrm{\theta } - \cos \,\mathrm{\theta } = \frac{1}{4} within the interval 0≤θ≤2π0 \le \mathrm{\theta } \le 2\mathrm{\pi }.
118 Medium
118 of 581
Application +4 | -1
The general solution of the equations: sin⁡θ=−32\sin \theta=-\frac{\sqrt{3}}{2} and tan⁡θ=3\tan \theta=\sqrt{3}
View answer and explanation
Correct option: B
2nπ+4π32 n \pi+\frac{4 \pi}{3}
Option B (2nπ+4π32 n \pi+\frac{{4 \pi}}{{3}}) is the correct general solution because it satisfies both sin⁡θ=−32\sin \theta=-\frac{{\sqrt{{3}}}}{{2}} and tan⁡θ=3\tan \theta=\sqrt{{3}}.
119 Medium
119 of 581
Application +4 | -1
If acos⁡2θ+bsin⁡2θ=ca \cos 2 \theta+b \sin 2 \theta=c has α\alpha and β\beta as its solutions, then tan⁡α+tan⁡β\tan \alpha+\tan \beta and tan⁡αtan⁡β\tan \alpha \tan \beta are, respectively
View answer and explanation
Correct option: A
2bc+a,c−ac+a\frac{2 b}{c+a}, \frac{c-a}{c+a}
Option A (2bc+a,c−ac+a\frac{{2 b}}{{c+a}}, \frac{{c-a}}{{c+a}}) is correct because it gives the correct expressions for tan⁡α+tan⁡β\tan \alpha + \tan \beta and tan⁡αtan⁡β\tan \alpha \tan \beta based on the given equation.
120 Medium
120 of 581
Application +4 | -1
If A+B+C=π\mathrm{A}+\mathrm{B}+\mathrm{C}=\pi, then cos⁡A+cos⁡B−cos⁡C=\cos \mathrm{A}+\cos \mathrm{B}-\cos \mathrm{C}=
View answer and explanation
Correct option: D
−1+4cos⁡A2cos⁡B2sin⁡C2-1+4 \cos \frac{\mathrm{A}}{2} \cos \frac{\mathrm{B}}{2} \sin \frac{\mathrm{C}}{2}
Option D (−1+4cos⁡A2cos⁡B2sin⁡C2-1+4 \cos \frac{{\mathrm{{A}}}}{{2}} \cos \frac{{\mathrm{{B}}}}{{2}} \sin \frac{{\mathrm{{C}}}}{{2}}) is correct because it represents the simplified form of cos⁡A+cos⁡B−cos⁡C\cos A + \cos B - \cos C when A+B+C=πA + B + C = \pi, using trigonometric identities.
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