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Mathematics 10 Online
OpenStudy (anonymous):

Simplify the Equation; Trigonometric Solving

OpenStudy (anonymous):

\[1-\sin^2x/\sin(x)-\csc(x)\] Ok, so I know that I should simplify the csc first into maybe "1/sin(x)", right? Then what..?

OpenStudy (anonymous):

@terenzreignz Hey, could you help me out? =)

terenzreignz (terenzreignz):

Ambiguity kills... is it like this~ \[\Large \frac{1-\sin^2(x)}{\sin(x)-\csc(x)}\]?

OpenStudy (anonymous):

Uhuh, that's it.

terenzreignz (terenzreignz):

Well the top... it should simplify into something... something elusive :D Remember the pythagorean identity? \[\large \cos^2(x) + \sin^2(x) = 1\]

OpenStudy (anonymous):

Yup, I do.

terenzreignz (terenzreignz):

Hang on...

terenzreignz (terenzreignz):

If we subtract \(\large \sin^2(x)\) from both sides of the pythagorean identity, we should end up with... \[\Large \cos^2(x) +\sin^2(x) \color{red}{-\sin^2(x)}=1\color{red}{-\sin^2(x)}\] Simplifying into \[\Large \cos^2(x) = 1-\sin^2(x)\] right?

OpenStudy (anonymous):

I believe so, yes =o

terenzreignz (terenzreignz):

the numerator then becomes...?

OpenStudy (anonymous):

cos^2(x)?

terenzreignz (terenzreignz):

Yup... \[\Large \frac{\cos^2(x)}{\sin(x) -\csc(x)}\]

terenzreignz (terenzreignz):

Now, the denominator could be written, such as you said, like this... \[\Large \frac{\cos^2(x)}{\sin(x) -\frac1{\sin(x)}}\]

terenzreignz (terenzreignz):

So... let's manipulate the denominator some more... \[\Large \frac{\cos^2(x)}{\frac{\sin^2(x)}{\sin(x)}-\frac1{\sin(x)}}= \frac{\cos^2(x)}{\frac{\sin^2(x) -1}{\sin(x)}}\]

OpenStudy (anonymous):

Wouldn't the "sin^2(x)" then become negative while the second denominator becomes sin^2(x)?

terenzreignz (terenzreignz):

Why would the \(\large \sin^2(x)\) be negative?

OpenStudy (anonymous):

Nevermind got confused. Please proceed =)

terenzreignz (terenzreignz):

remember this identity... \[\large \cos^2(x) + \sin^2(x) = 1\] It can also be rearranged into this... \[\Large \color{green}{\sin^2(x) -1 = \color{black}{-}\cos^2(x)}\] right?

OpenStudy (anonymous):

Right. Ok, so \[\cos^2(x)/-\cos^2(x)/\sin(x)\] . What next?

OpenStudy (anonymous):

Would that leave use -1 + sin(x)...?

terenzreignz (terenzreignz):

No, the \(\Large \sin(x)\) at the denominator can be brought to the numerator, like so... \[\Large \Large \frac{\sin(x)\cos^2(x)}{-\cos^2(x)}\] Now just simplify :P

OpenStudy (anonymous):

sin(x) - 1

terenzreignz (terenzreignz):

Nope... this happens... \[\Large \frac{\sin(x)\cancel{\cos^2(x)}}{-\cancel{\cos^2(x)}}=\frac{\sin(x)}{-1}\]

OpenStudy (anonymous):

Oh, well then it should be -sin(x)..?

terenzreignz (terenzreignz):

That's much better :P

OpenStudy (anonymous):

^_^ ok, thank you so much. I may need your help in a second, but it's just for verifying my answers if you don't mind.

terenzreignz (terenzreignz):

right, let's do it :P

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