Question

(sin A + cos A)^2 is equal to _____

(a) 1 + 2sin A cos A

(b) 1 – 2sin A cos A

(c) 2sin A cos A – 1

(d) 2sin A cos A + 1

This question was addressed to me in an international level competition.

The origin of the question is Trigonometric Identities in portion Trigonometry of Mathematics – Class 10

Answer 1

Correct option is (a) 1 + 2sin A cos A

Easiest explanation: (sin A + cos A)^2 = sin^2 A + cos^2 A + 2sin A cos A

= 1 + 2sin A cos A