Question

The point (15, 20) is on the terminal side of an angle drawn in standard position. How do you find the exact value of the cosine of the angle?

Answer 1

Find cos of an angle x.

Ans: `cos x = 3/5`

Explanation:

Call x the angle to be determined:
`tan x = y/x = 20/15 = 4/3.`
The hypotenuse h of the right triangle with 2 sides x and y is:

h^2 = x^2 + y^2 = 9 + 16 = 25 --> h = 5.
`cos x = x/h = 3/5`