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May 3rd, 2018, 03:49 AM   #1
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find the possible values of sin theta if cos theta = 2/3

Hello

1. Find the possible values of sin theta if:

a. Cos theta = 2/3 b. cos theta = - 3/sq13

Can someone explain the steps to take to find the values of the above? I have looked online and was not able to get a clear understanding what is needed to get the values which will help me with my exam next month.
Thank you very much.
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May 3rd, 2018, 06:02 AM   #2
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By Pythagoras, $\sin^2\theta+\cos^2\theta=1$, so

a) $\sin\theta=\pm\sqrt{1-\cos^2\theta}$. Use known values to complete the calculation.

You can employ a similar method for b).
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May 3rd, 2018, 06:09 AM   #3
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Thank you.
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