Find the general solutions of:

cos 50 + cos 30 = 0

Printable View

- May 14th 2006, 04:33 PMLilDragonflyTrigonometric equations
Find the general solutions of:

cos 50 + cos 30 = 0 - May 14th 2006, 06:52 PMThePerfectHackerQuote:

Originally Posted by**LilDragonfly**

$\displaystyle \cos x=a$ you know what to find all the solutions.

---------

Use cosine angle sum identity on,

$\displaystyle \cos 5x+\cos 3x=0$

To get,

$\displaystyle 2\cos 4x\cos x=0$

Thus, each factor is zero,

$\displaystyle \cos 4x=0$

$\displaystyle \cos x=0$