Please help I have tried to solve this already but I still don't understand it..

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

Write 17/20 as a decimal and as a percent.

Consider the functions below. function 1 function 2 function 3 select the statement which is true about the functions over the interval [1, 2] a b function 3 has the highest average rate of change function 2 and function 3 have the same average rate of change. function and function 3 have the same average rate of change function 2 has the lowest average rate of change d.