In triangle ABC, angle c is 90 degrees AB is 10 cosine B is 4/5 find AC.

In a right-angled triangle, the cosine of its acute angle is the ratio of the length of the adjacent leg to the length of the hypotenuse.

Then, in a right-angled triangle ABC:

CosABC = BC / AB.

BC = AB * CosABC = 10 * 4/5 = 8 cm.

By the cosine theorem, we determine the length of the leg AC.

AC ^ 2 = AB ^ 2 – BC ^ 2 = 100 – 64 = 36.

AC = 6 cm.

Answer: The length of the AC leg is 6 cm.



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