I NEED HELP PLEASE !!

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

The value of cos 30° is the same as which of the following?

Why is it so easy to buy on impulse and overspend with a credit card? what could you do to counteract this tendency?