How do I find the exact solutions algebraically for the following equation?

sin 2x sin x = cos x

Any help is appreciated.

Printable View

- December 1st 2009, 10:40 AMiluvmathbutitshardFind exact solutions algebraically?
How do I find the exact solutions algebraically for the following equation?

sin 2x sin x = cos x

Any help is appreciated. - December 1st 2009, 10:44 AMJameson
- December 1st 2009, 10:53 AMiluvmathbutitshard
Ok, so how would I simplify further?

- December 1st 2009, 10:57 AMJameson
- December 1st 2009, 11:04 AMiluvmathbutitshard
Ok, thank you. I got it now.

:) - December 1st 2009, 11:22 AMe^(i*pi)
Without knowing the domain you could potentially be dividing by 0 when cos(x)=0 if you cancel. It is better to take cos(x) from both sides and factor out cos(x)

Either or

This should give 3 principal solutions and there may be more or less depending on the domain (usually ) - December 1st 2009, 11:28 AMJameson
Very good observation. Thank you for pointing this out. (Clapping)