X2> 4x-20 which value of x makes the open sentence true?

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)

Evaluate the expression. (9 + 5)(3 + 2)0