Question

How do you solve the right triangle given it is a 72-18-90 triangle. The hypotenuse side is x, the adjacent side is 8, and the angle in between them is 72?

Answer 1

`x=38.5` (approximately)

Explanation:

By definition of cosine
`color(white)("XXX")cos(72^@)=8/x`

`color(white)("XXX")rArr x=8/cos(72^@)`

using a calculator, `cos(72^@)~~0.207912`

`color(white)("XXX")rArr x = 8/0.207912 ~~38.47787`