Question

Is sin (90°+x) = cos x.

(a) True

(b) False

I had been asked this question during an interview.

I'd like to ask this question from Trigonometric Functions of Sum and Difference of Two Angles-1 in chapter Trigonometric Functions of Mathematics – Class 11

Answer 1

The correct answer is (a) True

Explanation: sin (90°+x) = sin 90° cos x + cos 90° sin x {sin(x + y)=sin x cos y + cos x sin y}

= 1*cos x + 0*sin x

= cos x.