Distance between 3,-6 and -2,-5

Can somebody me out with this question

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

Given: ab ≅ bc and ao ≅ oc ok − angle bisector of ∠boc find: m∠aok