http://209.85.48.8/9963/162/upload/p2222992.gif

I'm no sure how to prove this equality true.

(Oh and I used an image instead of latex, because I don't know how, someone also tell me how to make to the power and cos?)

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- Dec 4th 2010, 09:07 PMCthulProving if it's true (Equality)
http://209.85.48.8/9963/162/upload/p2222992.gif

I'm no sure how to prove this equality true.

(Oh and I used an image instead of latex, because I don't know how, someone also tell me how to make to the power and cos?) - Dec 4th 2010, 09:18 PMProve It
It doesn't. You need to use the identity

.

So that means

. - Dec 4th 2010, 09:21 PMCthul
Thanks, that was helpful.

(And I got how to do the latex now) - Dec 5th 2010, 05:42 AMArchie Meade
When you get to

you can combine some of the squares to get 1.

Note that there is a difference between an equation and an identity.

An identity is true for all x.

An equation is true for certain x for which we solve. - Dec 5th 2010, 09:07 PMCthul
I have another that I'm not sure. I want to know how to prove its identity.

- Dec 5th 2010, 09:18 PMProve It
Start by noting that and use the angle sum identity to simplify.

Then note that and again use the angle sum identity to simplify. - Dec 6th 2010, 01:33 PMArchie Meade
- Dec 6th 2010, 04:05 PMSoroban
Hello, Cthul!

Quote:

I'm no sure how to prove this equality true.

I'm not surprised . . . The statement is not true.

- Dec 7th 2010, 11:59 AMTheCoffeeMachine
- Dec 7th 2010, 01:13 PMArchie Meade
Though if anyone got suckered into thinking it was an equation to be solved, then

is a solution among others...

(Doh) - Dec 8th 2010, 02:26 AMCthul
Thanks for your response.