In triangle ABC, angle C is 90 degrees, cosA = 24/25. Find cos B.

univerkov | July 29, 2021 | education

For the solution, we use the basic trigonometric identities.

Sin2A + Cos2A = 1.

Sin2A = 1 – Cos2A = 1 – (24/25) ^ 2 = 1 – 576/625 = 49/625.

SinA = √ (49/625) = 7/25.

In a right-angled triangle, the sine of one acute angle is equal to the cosine of another acute angle.

Then CosB = SinA = 7/25.

Answer: CosB = 7/25.

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