Please help as much as u can!!

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

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)

Select all the correct locations on the table. consider the following expression. 76.493 select "equivalent" or "not equivalent" to indicate whether the expression above is equivalent or not equivalent to the values or expressions in the last column equivalent not equivalent 343 equivalent not equivalent 49 78.498 78.498 75.493 equivalent not equivalent 75.7 equivalent not equivalent