posted by mary .
Can someone please help me with this?
Find all solutions to the equation in the interval [0,2pi)
I know I have to use some sort of identity, but I have no idea how to go about to solve this.
Yes, by making use of the identity
cos2x = cos²x-sin²x=1-2sin²x, the given equation can be transformed to:
which is a quadratic in sin(x).
Solving the quadratic by factoring,
or sin(x)=1/2 or sin(x)=-1
Find all roots in the interval [0,2π].
Thank you very much for the help
Trig. :) -
You are welcome!