cos3X=sinX

Find X, 0 degree < x < 360 degree

Thanks in advance

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- Sep 6th 2008, 01:22 AMose90Solving trigo
cos3X=sinX

Find X, 0 degree < x < 360 degree

Thanks in advance - Sep 6th 2008, 01:43 AMmr fantastic
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. - Sep 6th 2008, 02:01 AMose90
Thank you very much!