# Trig!!!

• January 27th 2008, 02:39 PM
Happy1234
Trig!!!
Hello!!! i really need help with TRIG!! hi dont understand the relationship betwek trig functions and finding the equivalent trig fucntion

for example..

Prove algebraically

tan = cot(pi/2 - x)
• January 27th 2008, 02:57 PM
mr fantastic
Quote:

Originally Posted by Happy1234
Hello!!! i really need help with TRIG!! hi dont understand the relationship betwek trig functions and finding the equivalent trig fucntion

for example..

Prove algebraically

tan x = cot(pi/2 - x) Red edit by Mr F.

$\cot \left( \frac{\pi}{2} - x \right) = \frac{\cos \left( \frac{\pi}{2} - x \right)}{\sin \left( \frac{\pi}{2} - x \right)} = \frac{\sin x}{\cos x} = \tan x$.

Things you are totally expected to know (for this particular question, anyway. Undoubtedly there are other basic things you are expected to know):

1. $\cot \theta = \frac{\cos \theta}{\sin \theta}$.

2. Supplementary angle formulae: $\cos \left( \frac{\pi}{2} - x \right) = \sin x \,$ and $\sin \left( \frac{\pi}{2} - x \right) = \cos x$.

Perhaps the reason you're struggling with these types of questions is that your knowledge bank is low on funds - time to start making deposits .....