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Mathematics 7 Online
OpenStudy (anonymous):

what are all the solutions of 5sin(theta)-4=2sin(theta)-4

OpenStudy (p0sitr0n):

replace sin theta by x and solve

OpenStudy (solomonzelman):

\[5Sinx-4=2Sinx-4\]let Sinx=a\[Sinx=a\] \[5Sinx-4=2Sinx-4\]\[5Sinx=2Sinx\]

OpenStudy (solomonzelman):

\[Sinx=0\]\[x=?\]

OpenStudy (solomonzelman):

I'll tell you this rule.\[Sinx=0~~~~~~~~~~~x=0\]

OpenStudy (solomonzelman):

Do you get it?

OpenStudy (anonymous):

I don't understand what to do with the 5 and the 2

OpenStudy (solomonzelman):

Are you clear till\[5~Sinx=2~Sinx\]

OpenStudy (anonymous):

yes

OpenStudy (solomonzelman):

So now the "COMMON SENSE" comes to rescue. \[5~Sinx=2~Sinx\]let Sin x = number OR let Sinx=a \[5a=2a\]this can only be true when a=0, so\[Sin~x=0\]

OpenStudy (anonymous):

what about pi?

OpenStudy (solomonzelman):

pi?

OpenStudy (anonymous):

in my work sheet the is 0, 2pi, pi or 0 , 2pi

OpenStudy (solomonzelman):

read what you wrote please.

OpenStudy (anonymous):

like the options are: a. 0, 2pi, pi b. 0, pi

OpenStudy (solomonzelman):

Oh, OK.

OpenStudy (solomonzelman):

well looking over the work, you can clearly see that Sin x=0 must be true. So your answer would be \[Sin^{-1}0\]which is ZERO. it's not pi or anything like that.

OpenStudy (anonymous):

thank you

OpenStudy (solomonzelman):

Anytime, I'm not good at math, but tried my best.

OpenStudy (anonymous):

Actually, the answer would be 2pi*k...where k is any integer. Think of all of the infinite possibilities when co-terminal angles come to mind.

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