What are the steps for solving this?

Question

Directions Use the quadratic formula to solve the equation in the interval [0,2PI). Then use a graphing utility to approximate the angle x.

4cos^2x-4cosx-1=0

thanks.

Answer 1

quadratic equation?

cosx= (4+-sqrt(16+4))/8

graph y=4cos^2 x - 4cosx + 1 and note where it crosses the y=0 axis.