Ido not understand how to do these following questions

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

The median am of triangle ∆abc is half the length of the side towards which it is drawn, bc . prove that triangle ∆abc is a right triangle, and find angle mac and abm

Calculate the total payback for a $3,500 loan at 8% annual interest with monthly payments for two years. show all of your steps. use the formula, m = pm(1 + m)^na/(1 + m)^na - 1, as needed.