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Mathematics 23 Online
OpenStudy (anonymous):

Trigonometry question (Please help)

OpenStudy (anonymous):

If 2sinx= 1, π/2 < x < π and √2 cos y =1 , 3 π/2 < y < 2 π , find the value of (tanx+tany )/(cosx-cosy)

OpenStudy (anonymous):

I just need a hint i will show what i did

OpenStudy (ranga):

You can find x and y by taking the inverse sine and cosine respectively. Just make sure that x and y are in the proper interval given. Once x and y are known, the rest can be figured out.

OpenStudy (anonymous):

We need a calc for inverse

OpenStudy (ranga):

These are standard angles in the unit circle.

OpenStudy (anonymous):

Wait i will show what i did

OpenStudy (anonymous):

\[\cos y =1/\sqrt{2}\] \[\sin ^{2}y + \cos^{2}y =1 \] \[\sin^{2}y=0.5 \] \[\sin y = -\sqrt{0.5}\] Following the same method \[Cos x = \sqrt{3}/2\] \[\tan x = 1/\sqrt{3}\]

OpenStudy (anonymous):

Is that correct ^

OpenStudy (ranga):

sin(y) = -sqrt(1/2) is correct. But x is in the second quadrant where cos(x) is negative.

OpenStudy (anonymous):

\[-\sqrt{3}/2\] ?

OpenStudy (ranga):

yes. so tan(x) will be negative too.

OpenStudy (anonymous):

\[[-(1/\sqrt{3}) + (-1)]/-(\sqrt{3})/2- (1/\sqrt{2})]\]

OpenStudy (ranga):

Yes. You have to simplify them and it would take some work.

OpenStudy (anonymous):

i simplified it

OpenStudy (anonymous):

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