SOLUTION: 2cos to the power 2 theta =cos theta

Algebra ->  Trigonometry-basics -> SOLUTION: 2cos to the power 2 theta =cos theta       Log On


   

Question 1181370: 2cos to the power 2 theta =cos theta
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

2cos%5E2+%28theta%29+=cos%28+theta%29
2cos%5E2%28theta%29-cos%28+theta%29+=0
%282cos%28theta%29-1%29cos%28+theta%29+=0
solutions:
cos%28+theta%29+=0
theta+=cos%5E-1%28+0%29
theta+=pi%2F2

2cos%28theta%29-1=0
cos%28theta%29+=1%2F2
theta=cos%5E-1%281%2F2%29+
theta=pi%2F3

cosine periodicity is 2pi

all the solutions:
theta=pi%2F3%2B2pi%2An
theta=5p%2F3%2B2pi%2An
theta=pi2%2B2pi%2An
theta=3pi%2F2%2B2pi%2An
Degrees:
theta=60%2B360°*n
theta=300%2B360°*n
theta=90%2B360°*n
theta=270%2B360°*n