In triangle ABC, angle C is 90 °, sinA = 0.25. Find cosB.

Given:
ABC – right triangle;
Angle C = 90 degrees;
sin A = 0.25;
Find cos b.
Decision:
In order to find the cos b of the triangle ABC, we use the formulas:
cos b = BC / AB; sin b = AC / AB;
cos a = AC / AB; sin a = BC / AB:
Hence we see that, cos b = BC / AB = sin a;
Since sin a = 0.25, then n substitute the known values into the formula and find cos b
cos b = BC / AB = sin a = 0.25.
As a result, we got that cos b = 0.25.
Answer: cos b = 0.25.