solve my questions I beg u

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

Which statement best explains why ben uses the width hi to create the arc at j from point k