Need help with number 2 please.

The tile along the edge of a triangular community pool needs to be replaced? ?

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

What is the name of a polygon that has four congruent sides and theses angle measures 60,120,60,120?