Answer:
Step-by-step explanation:
You are correct in starting with sin²Ф + cos²Ф = 1.
We are told that cos Ф = -8/17 and that the angle Ф is in Quadrant II.
We want to find sin Ф. Solve sin²Ф + cos²Ф = 1 for sin²Ф:
sin²Ф = 1 - cos²Ф
= 1 - (8)²/(-17)² = 1 - 64/289 = 289/289 - 64/289 = 225/289
Taking the square root of this result, and remembering that Ф is in Quadrant II:
sin Ф = +√225/289 = +15/17
So your answer is just about right, except that you write "sin" without an argument (angle).
