Solve for 0 less than or equal to x less than or equal to 360.
a) cos2x = tan2x
b) cos3x + cosx = 0
Many thanks in advance.
Multiply both sides by
Rearrange and use the Pythagorean identity sin^2(x) + cos^2(x) = 1:
Use the quadratic formula:
Although it's kind of long, but you have to use the identities:
Keep expanding the cosines/sines until you get everything in the same angle.