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Mathematics 9 Online
OpenStudy (allieeslabae):

How do you simplify this trig expression?

OpenStudy (allieeslabae):

\[(\sin ^2\theta)/(1+\cos \theta)\]

OpenStudy (mathmale):

Hints: rewrite (sin theta)^2 in terms of cos theta. apply this principle:\[\frac{ 1-g^2 }{ 1-g }=1+g\]

OpenStudy (allieeslabae):

Awesome thanks! Would it be \[(\cos \theta)\]

OpenStudy (allieeslabae):

@sshayer

OpenStudy (sshayer):

no you can solve either multiply each the numerator and denominator by 1- cos theta

OpenStudy (sshayer):

or use \[\sin ^2 \theta+\cos ^2 \theta=1,\sin ^2 \theta=1-\cos ^2 \theta= \left( ? \right)\left( ? \right) \]

OpenStudy (allieeslabae):

Ohhh really? Okay so I got \[(\sin ^2\theta)\] but that's not an answer choice...

OpenStudy (mathmale):

With what are you replacing (sin theta)^2? Be specific, please. How would you ssimplify your result? Show all steps, please.

OpenStudy (sshayer):

\[\frac{ \sin ^2 \theta }{ 1+\cos \theta }=\frac{ 1-\cos ^2\theta }{ 1+\cos \theta }=\frac{ (?+?)(?-?) }{ (1+\cos \theta )} \]

OpenStudy (sshayer):

make factors of numerator.

OpenStudy (allieeslabae):

I still think it's \[(1-\cos \theta)/(\cos \theta)\]

OpenStudy (sshayer):

\[a^2-b^2=\left( a+b \right)\left( a-b \right)\] \[1-\cos ^2\theta=1^2-\left( \cos \theta \right)^2=?\] can you make factors now ?

OpenStudy (sshayer):

a=1,b=cos theta

OpenStudy (allieeslabae):

Bwahaha That makes sense thank you!

OpenStudy (mathmale):

this is the key; apply this info to the problem at hand.\[1-\cos ^2\theta=1^2-\left( \cos \theta \right)^2=?\]

OpenStudy (mathmale):

Hint: You've GOT TO FACTOR the right side of the equation above.

OpenStudy (allieeslabae):

\[\theta=\pi/2, \pm \pi n, \pm2\pi n\]

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