Question

simplify the trigonometric expression sin^2 theta/1+cos theta

Answer 1

Is there a trig identity you can substitute for sin^2 theta?

Answer 2

I have no idea what I'm doing. I don't even know what that is.

Answer 3

Are you familiar with sin^2 theta + cos^2 theta = 1?

Answer 4

No.

Answer 5

use sin^theta = 1 - cos^2 theta and after that use rationalisation

Answer 6

Since sin^2 theta + cos^2 theta = 1, then 1 - cos^2 theta = sin^2 theta, so you can substitute

Answer 7

sin^2 theta/(1 + cos theta) = (1-cos^2 theta)/(1 + cos theta)

Answer 8

I think I might just have to go back and relearn a whole bunch of stuff because I am not understanding any of this

Answer 9

This might help: http://www.intmath.com/trigonometric-functions/2-sin-cos-tan-csc-sec-cot.php

Answer 10

Although I just realized that trig identities are not included there. But this may come in handy: http://www.sosmath.com/trig/Trig5/trig5/trig5.html

Answer 11

thank you

Answer 12

The link to the first site provides a quick discussion of the different trigonometric ratios (sine, cosine, tangent, cosecant, secant and cotangent).

Answer 13

The second link has useful trig "identities", equivalent expressions that you can substitute for each other

Answer 14

So in the problem you have, you can substitute (1 - cos^2 theta for sin^2 theta). The reason that is useful is because you can then factor 1 - cos^2 theta. 1 - cos^2 theta = (1 + cos theta)(1 - cos theta)

Answer 15

So your expression then becomes (1 + cos theta)(1- cos theta)/(1 + cos theta) The (1 + cos theta) in the numerator and denominator cancel out. And, as rishavraj said, you are left with the answer: 1 - cos theta

Answer 16

So I hope that is somewhat helpful. :)