Trigonometric Identites

**spedman** · December 11th 2007, 06:31 AM

I need some help on 15 identites problems to help me study for my math final.

they range from problems like

sec^2x csc^2x = sec^2x + csc^2x

to

tan(pi/5) - tan(pi/30) = (-1/root 3)
1+tan(pi/5) tan(pi/30)

Anyone think they would be able to help me?

**kalagota** · December 11th 2007, 06:36 AM

when is your finals? and how do you want us to help you?

**spedman** · December 11th 2007, 06:37 AM

my final is on thursday. and anything anyone could really do would be great. whether it be do the problems out, or help me figure out how to start it.

**kalagota** · December 11th 2007, 06:48 AM

ahh, so you want us to solve the problems you gave above..

so, i think, the first one is easy.. note that $\sec^2 x = tan^2x + 1$ and $\tan^2 x = \frac{\sin^2x}{\cos^2} =\frac{\sec^2x}{\csc^2x}$ , so ithink, you can do it..

**kalagota** · December 11th 2007, 06:51 AM

for the other one, take note of sum/difference in tangents.

$\tan (A \pm B) = \frac{\tan A \pm \tan b}{1 \mp \tan A \tan B}$

so can you recognize that $A = \frac{\pi}{5}$ and $B = \frac{\pi}{30}$ ?

**spedman** · December 11th 2007, 08:04 AM

They are blurry and somewhat hard to read, but if anyone wants to take a crack at some of them they are here:

http://img407.imageshack.us/img407/5696/math1lh2.jpg

http://img509.imageshack.us/img509/9642/math2fw6.jpg

http://img70.imageshack.us/img70/7996/math3hn7.jpg

http://img69.imageshack.us/img69/7543/dsc00180on3.jpg

15 problems. If anyone can't read something just let me know.

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