Read the description below Find cos(theta) and explain the steps utilized to complete the previous problem

Question

Given tan(theta)=-5/7 in quadrant ll, find cos(theta)

 

 

 

 

 

explain the steps utilized to complete the previous problem 

Answer 1

A usual way to work a problem like this is to draw a 'reference angle' with its terminal side being a ray beginning at the origin and containing point (-7,5).  Now calculate the hypotenuse of the reference triangle (it's square root of (49+25)).

 

Cos θ = -7/√74