PQ has endpoints P(2, 1) and Q(5,5). If PQ and PR have the same length and P, Q, and R are not
collinear, which could be the coordinates of R?

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b