9.6

3: Reduce 8/10 to 4/5.

7: Do sin^-1 on each side of the equation.

13: Set up a tangent equation (since you have the two legs but not the hypotenuse) and then take the tangent inverse of each side.

17: Set up a function that involves the hypotenuse.

30: The sin function finds a ratio based on an angle, and the sin^-1 function finds an angle based on a ratio.

31: This would be finding the angle for which the opposite side is 1.2 times as long as the hypotenuse.

33: You can cancel the denominators by multiplying each side by them.