I need help please, Last ones!

Acylinder has volume 45π and radius 3. what is it’s height?

Boris needs to buy plastic spoons. brand a has a box 42 spoons for $2.37. brand b has a box of 72 spoons for $3.57. find the unit price for each brand. then state which brand is the better buy based on the unit price. round your answer to the nearest cent.

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.