Which of the following expressions is equal to for every acute angle ?

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

Problem

Which of the following expressions is equal to

1

for every acute angle

A

? (a)

\tan^2 A + 1

(b)

\sin^2 A - \cos^2 A

(c)

\sin^2 A + \cos^2 A

(d)

\sin A\cos A