Trig functions, finding co-ordinates

[TheRedDevil18]

Homework Statement

I have a graph with the functions f(x)=sin2x and g(x)=cosx. The 2 graphs intersect at point B. They want me to find the co-ordinates of B.

Homework Equations

The Attempt at a Solution

Must I equate the two graphs?

sin2x = cosx
2x = 90-x, 3x = 90, x=30 or 2x = 180-(90-x), x=90

It doesn't seem right, is their any other steps?

 

[Saitama]

Aren't you given any specific range within which you want the solution, both the graphs intersect at many points.

 

[TheRedDevil18]

they say that f and g intersect at A(30:0.87) and B.
the domain is xE[0;270].
Thats all that is given.

 

[jbunniii]

Do you know a trig identity for sin(2x)?