# [SOLVED] Help with trig identities proof

• November 19th 2009, 03:24 PM
83457
[SOLVED] Help with trig identities proof
I'm stuck on the trig identities proof and I was wondering if someone could get me started.

http://i47.tinypic.com/dfgg8x.gif
• November 19th 2009, 03:49 PM
Soroban
Hello, 83457!

Quote:

$(\tan x + \cot x)^2 \:=\:\sec^4\!x\cot^2\!x$

Left side: . $(\tan x + \cot x)^2 \;=\;\left(\tan x + \frac{1}{\tan x}\right)^2 \;=\;\left(\frac{\tan^2\!x + 1}{\tan x}\right)^2 \;=$ . $\left(\frac{\sec^2\!x}{\tan x}\right)^2 \;=\;\frac{\sec^4\!x}{\tan^2\!x} \;=\;\sec^4\!x\cot^2\!x$