# In triangle ABC, angle C is 90 °, sinA = 0.6. Find cosB.

September 15, 2021 | education

| Given:

ABC – right triangle;

Angle C = 90 °;

sin A = 0.8;

Find cos B.

Solution:

We apply the formula: sin A = BC / AB.

Since cos B = BC / AB, then we get: sin A = BC / AB = cos B.

Hence, we obtain that cos B = sin A.

Substitute the known value sin A = 0.8 into the expression cos B = sin A and find cos B.

cos B = sin A = 0.8.

This means that cos B = 0.8.

Answer: cos B = 0.8.

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