9.5

2: It’s either sine, cosine, or tangent.

4: Three of these are all the same value.

6: The sine of one angle is the cosine of the other angle.

9: It’s best if you simplify, but not required in this case.

12: See #6.

21: Start with sin 71° or cos 71°, because you know the length of the hypotenuse and sine and cosine both use the hypotenuse.

23: After setting up the initial equation, multiply both sides by the denominator, whether it is a number or a variable.

26: Two of the ratios are 2 over 4.

27: Try each possibility, and simplify to see if equals √3/2.

30: Change the function, or change the ratio.

31: Set up sine, cosine, or tangent equation with one variable, and multiply each side by the denominator.

48: Both are correct (explain why).

53: To divide by a fraction, multiply by its reciprocal.