# In triangle ABC, angle C is 90 degrees, AC = B, Cos A = 5/7 Find AB.

August 29, 2021 | education

| Given:

ABC – right triangle;

Angle C = 90 degrees;

AC = 5;

cos A = 5/7;

Find AB.

Solution:

In order to find the hypotenuse AB of the triangle ABC, we use the formula:

cos A = AC / AB.

Hence, AB = AC / cos a;

Substitute the known values into the formula and find the hypotenuse AB.

AB = 5 / (5/7) = 5/1 * 7/5 = 1/1 * 7/1 = 7/1 = 7;

Answer: AB = 7.

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