In triangle ABC, angle C = 90 degrees, cosB = √19 / 10, find cos A.

univerkov | April 27, 2021 | education

Since Cos = √19 / 10, the length of the BC leg = X * √19 cm, and the length of the hypotenuse is 10 * X cm.

Then, by the Pythagorean theorem, AC ^ 2 = AB ^ 2 – BC ^ 2 = 100 – 19 = 81.

AC = 9 cm.

Determine the leg of the angle BAC.

CosBAC = AC / AB = 9/10.

Answer: The cosine of the angle BAC is 9/10.

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