In any , is equal…

MATHEMATICS · Single correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

In any

\triangle ABC

\left(\frac{b-c}{a}\right)\cos^2\left(\frac{A}{2}\right)+\left(\frac{c-a}{b}\right)\cos^2\left(\frac{B}{2}\right)+\left(\frac{a-b}{c}\right)\cos^2\left(\frac{C}{2}\right)

is equal to (1)

\frac{b^2-c^2}{a^2}

(2)

\frac{c^2-a^2}{b^2}

(3)

\frac{a^2-b^2}{c^2}

(4)

0