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What are trig identities?can you please help me with this problem?

Posted 10 years ago

Hello, 1) I'm confused on what are exactly all the trig identities. My professor is very unclear. What are the trig identities used for? Is is just something I need memorize?

2) Can someone help me prove this:

sin(x)/(1+cos(x)) + (1+cos(x))/sin(x) = 2csc(x)

Any help would be appreciated. Thank you.

POSTED BY: K M
3 Replies
Posted 10 years ago

Thank you so much. I understand it now. I needed to know it for my midterm today.

POSTED BY: K M

Here's a simplified step-by-step solution:

sin(x)/(1+cos(x)) + (1+cos(x))/sin(x) = 2csc(x)

Multiply by sin(x)

sin(x)^2/(1+cos(x)) + (1+cos(x))= 2

Use sin(x)^2=1-cos(x)^2={1+cos(x)) (1-cos(x))

Thus 1-cos(x) +1+cos(x) = 2

QED

POSTED BY: S M Blinder

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POSTED BY: Simon Cadrin
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