Ah, I've always sucked at doing proofs, so I'd like help with these two;

Prove that

Prove that

Sorry that I haven't shown my beginning steps, I'll work on it while I wait for a response. (Rofl) Thanks in advance for any help (Heart)

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- Feb 20th 2010, 05:46 PMStonerPenguinHelp! Proving trigonometic identities!
Ah, I've always sucked at doing proofs, so I'd like help with these two;

Prove that

Prove that

Sorry that I haven't shown my beginning steps, I'll work on it while I wait for a response. (Rofl) Thanks in advance for any help (Heart) - Feb 20th 2010, 06:11 PMpickslides
- Feb 20th 2010, 06:12 PMGusbob
- Feb 22nd 2010, 08:15 AMStonerPenguin
Wow! Thanks guys! Lots of smart people from Austrailia! (Rofl) I really appreciate the help, but Gusbob, the second one doesn't look right to me;

I don't see how

Doesn't ? And even if I'm being stupid and you are right, I'm suppose to transform the it into not 1. (I'm so sorry if I sound too harsh or ungrateful, I just want makes sure it's right D: )

Anywho, here's what I got, does this look right?

Given

Swapping the sides around

Simplify by multiplying

Reciprocal Identity

Pythagorean Identity

TAH-DAH~

Also, here's two other question I'd like to double check;

Find the exact value of cos 105° without using tables or a calculator.

(Using the addition formula for cosine)

Is that right?

And, "Find the exact value of tan 15° without using tables or a calculator."

(Using a Half-Angle formula for the tangent)

_______

....

=

BTW How do you put subordinate fractions using the math bbcode? That was the only way I could think to do it.