Factor. 81a36−64b16 (9a6−8b4)(9a6+8b4) (9a18−8b8)(9a18+8b8) (9a6−8b4)2 (9a18−8b8)2

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