Question

in right triangle abc, when angles a and b add up to 90 degrees, what is the cosine of b equal to?
a. sin b
c. sin a
b. tan a
d. cos a
please select the best answer from the choices provided
a
b
c
d

Explanation:

Step1: Recall trigonometric co - function identity

In a right - triangle, if \(A + B=90^{\circ}\), then \(\cos B=\sin(90^{\circ}-B)\).
Since \(A + B = 90^{\circ}\), we have \(90^{\circ}-B = A\).
So \(\cos B=\sin A\).

Answer:

C. \(\sin A\)