You can put this solution on YOUR website! for which value of theta is this expression undefined?
Sin theta/ (1 + 2 cos(t))
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Undefined when 1+2cos(t) = 0
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Solve:: 1 + 2cos(t) = 9
cos(t) = -1/2
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t = (2/3)pi or 60 degrees
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Cheers,
Stan H.
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