Question

Ismail tried to prove that sin(θ) = cos(90°− θ) using the following diagram. His proof is not correct.

What is the first mistake in Ismail's proof?

Answer 1

c

Explanation:

Answer 2

• C. Ismail used the wrong sides in his ratio for cos (90 - θ)

Explanation:

All steps correct apart from:

• cos (90° - θ) = AC/BC

It should be

• cos (90° - θ) = AB/BC

Correct choice is C