The two scalene triangles shown are similar but not congruent. ∠ ≅ ∠ ∠
R
Q
S

≅

∠
Q
S
P
. Which statement is true?

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