Prove that

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- February 12th 2010, 10:24 AMgary223Prove tan
Prove that

- February 12th 2010, 10:29 AMKrizalid
straightforward, just use the formula for

- February 12th 2010, 10:31 AMgary223
I've never done this type question before, could you post how its done please. I know I have to use the formula but how is it done?

- February 12th 2010, 10:32 AMKrizalid
- February 12th 2010, 10:38 AMgary223
So what is x and y? Is it and ?

- February 12th 2010, 10:43 AMskeeter
- February 12th 2010, 10:57 AMgary223
- February 12th 2010, 11:04 AMskeeter
- February 12th 2010, 11:27 AMgary223
- February 12th 2010, 11:30 AMskeeter
- February 12th 2010, 11:38 AMgary223
- February 13th 2010, 07:42 AMgary223
Or is it

Sorry for double post but I wanna get this. - February 13th 2010, 07:59 AMskeeter
you were asked to prove that

Krizalid gave you the sum identity for tangent ...

my initial post basically told you to substitute for and for ...

using the fact that ...

the original equation is proved ... you're done. - February 13th 2010, 08:07 AMgary223
Wow, it seems so easy once you do it. Thanks.

- February 13th 2010, 11:58 PMPunch
Note that special angles exist, which are basically, sine, tangent and cosine of 30, 45, 60and 90. And you are required to recognise them..