Atriangle has angles that measure 30, 60, 90. the hypotenuse of the triangle measures 10 inches. which is the best estimate for the perimeter of the triangle?

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