Question 912213
(15/17, 8/17) is in quadrant I


Adding pi to the angle rotates it 180 degrees to quadrant III where both x and y are negative, so 


P(t+pi)=(-15/17, -8/17)


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The same thing happens when you subtract pi because you will land in the same place rotating 180 degrees CCW or CW


P(t-pi)=(-15/17, -8/17)


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P(-t) = (15/17, -8/17)


because you go below the x axis when you have a negative angle

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Take the angle -t and rotate it 180 degrees. You'll go from Q4 to Q2


So x is negative, y is positive


P(-t-pi) = (-15/17, 8/17)

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