In $\triangle A B C(a+b)(a-b)=c(b+c)$, the measure of angle $A$, is-

JEE MATHEMATICS MCQ: PROPERTIES OF TRIANGLES

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Application +4 | -1

\triangle A B C(a+b)(a-b)=c(b+c)

, the measure of angle

A

, is-

View answer and explanation

Correct option: D

120^{\circ}

Option D (

120^{\circ}

) is correct because by applying the law of cosines and simplifying the given equation, we find that

\cos A = -1/2

, which corresponds to an angle of

120^{\circ}

Practice All Chapter MCQs →

{p_1},{p_2},{p_3}

\Delta \;ABC

A,B,C

\Delta

p_1^{ - 2} + p_2^{ - 2} + p_3^{ - 2}

5k,\;6k,\;5k

k

\Delta \,ABC

a = \left( {b - c} \right)\sec \theta

\frac{{2\,\sqrt {bc} }}{{b - c}}\,\,\sin \,\,\frac{A}{2} =

\Delta \;ABC,\frac{{b + c}}{a}

\Delta = {a^2} - {\left( {b - c} \right)^2}

\Delta

\Delta \;ABC

\tan A

A

2 s