Practice!

Sample Problem

Find the exact solutions of sin2x-cos x=0.

Solution

Sin2x-cosx=0

2sinxcosx-cosx=0

cosx(2sin x-1)=0

cosx=0 or 2sinx-1=0

cosx=0 : x=π/2, 3π/2

2sinx-1=0

Sinx=1/2: x=π/6, 5π/6