You can put this solution on YOUR website! Point (3,-5) is on the terminal arm of angle theta.
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If x = 3 and y = -5, r = sqrt[3^2+5^2] = sqrt[34]
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sin(theta) = y/r = 3/sqrt(34)
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sec(theta) = r/x = sqrt(34)/(-5) = -sqrt(34)/5
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Cheers,
Stan H.