What is the approximate volume of the cone height is 6 cm and the radius is 9 cm

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

Astudent draws two parabolas both parabolas cross the x axis at (-4,0) and (6,0) the y intercept of the first parabolas is (0,-12). the y intercept of the second parabola is (0,-24) what is the positive difference between the a values for the two functions that describe the parabolas

For the sequence [tex]a_{n} = 2n/(n+1)[/tex], what is the value of [tex]a_{10}[/tex]