Question #a6825

1 Answer
Feb 17, 2018

See below

Explanation:

Instead of cos(2x)=0, think of the equation as cos(theta)=0, where theta=2x

Since costheta=0 at theta=pi/2 and theta=(3pi)/2, then by substitution,

cos(2x)=0 at 2x=pi/2 and 2x=(3pi)/2

Solve each equation separately

2x=pi/2
x=pi/2xx1/2
x=pi/4

2x=(3pi)/2
x=(3pi)/2xx1/2
x=(3pi)/4