Andrea receives a $40 gift card to use at a town pool. It costs her $8 per visit to swim. A function relating the value of the gift card, v, to the number of visits,
n, is v(n) = 40 - 8n.

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