In triangle ABC, angle C = 90, AB = 75, BC = 45. Find Cos A

As we know from the school mathematics course, the cosine of an angle can be calculated through the ratio of the leg, which will be adjacent to this angle, to the hypotenuse.

Based on the condition of the problem, the side AB is the hypotenuse, it is opposite the corner C.

Let us determine what the leg we need will be equal to, when from the condition of the task we know that BC = 45:

√ (75 ^ 2 – 45 ^ 2) = √ (5625 – 2025) = √3600 = 60.

Let us determine what the cosine of the angle A will equal:

60: 75 = 0.8.

Answer: Under these initial conditions, cos A = 0.8.