cos3X=sinX
Find X, 0 degree < x < 360 degree
Thanks in advance
There's the hard way and the easy way. Personally I like the easy way best:
From the complementary angle formulae: $\displaystyle \cos (3x) = \sin x \Rightarrow \cos (3x) = \cos (90 - x)$.
Case 1: $\displaystyle 3x = 90 - x + 360 n$ where n is an integer.
Solve for x and substitute appropriate values of n to get all values of x satisfying the given domain.
Case 2: $\displaystyle 3x = -(90 - x) + 360 n$ where n is an integer.
Solve for x and substitute appropriate values of n to get all values of x satisfying the given domain.