Question

Select the true statement about triangle ABC.

A. sin A = tan C
B. sin A = sin C
C. sin A = cos B
D. sin A = cos C
10
B
13
12
A

Answer 1

D

Explanation:

using the cofunction identity

sin x = cos(90 - x), that is

sin(angle) = cos(complement)

note : complementary angles, sum to 90°

given B is a right angle, 90° , in Δ ABC

Then A + B = 90° ( sum of angles in triangle = 180° )

thus B is the complement of A , so

sinA = cosB