Atrain traveled 300 km in 5 hours and then increased in speed, traveling the final 100 km in 1.5 hours. what was the train's average speed in km/h? 66.7 km/h 60 km/h 61.5 km/h 54 km/h

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