Answer: It would be A, 12.28 degrees.
Step-by-step explanation: Remember the acronym for sin cos tan, SOH CAH TOA. Where s c and t stand for sin cos tan, and the A stands for adjacent side, O stands for the opposite, and H stands for the hypotenuse. Here, side AC is opposite to the angle 17 degrees, and we have the measure of the hypotenuse side. So plug in accordingly, sin 17 = x /42. Use any variable for the unknown side. Multiply 42 to sin 17 to get 12.279, which rounds to 12.28 degrees. Make sure your calculator is in degree mode, since we are dealing with degrees.