Question

solve: sin^2theta-cos^2theta= 1+costheta

Answer 1

Hint:
Use the relationship sin^2theta + cos^2theta = 1
to replace the sin^2theta term in your equation.
Then you will have an equation with only cos's.(no sin's)

Answer 2

cos^2theta - sin^2theta= cos(2theta i thought?

Answer 3

No, don't use that one. Use
\[\sin ^{2}\theta + \cos ^{2}\theta = 1\]

Answer 4

solve that for sin^2(theta) and you get
sin^2(theta) = 1 - cos^2(theta)

Answer 5

Plug that into your original equation for sin^2(theta).
Next step : get 0 on 1 side and figure out which values of theta make the other side = 0

Answer 6

that makes so much more sense!!! thanks

Answer 7

no problem