Lines t and s (picture attached)

which of the following pair of angles are vertical?

a. 3 and 4

b. 1 and 3

c. 3 and 2

d. 4 and 1

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