How do you find the volume to a shape in math

In the figure dhg fhe which statement is true by cpctc

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

Aperpendicular bisector, cd is drawn through point con ab if the coordinates of point a are (-3, 2) and the coordinates of point b are (7,6), the x-intercept of cd is point lies on cd.