1.
78.5° would be the answer if the angle had been acute, but you wanted the angle in the 4th quadrant
so Ø = 360 - 78.463 = 281.5°
check by taking cos 281.5°
2.
Again you want -90 ≤ Ø ≤ 90, which would be quadrant I or quadrant IV
but for sinØ = .95, the sine is positive in the first quadrant and not in the IV
so you are correct
Again, you could have checked your answer by taking sin 71.8°
1. cos theta = 0.2 for 270 degrees <= theta <= 360 degrees.
Ans: 78.5 degs?
2. sin theta = 0.95 for -90 degrees <= theta <= 90 degrees.
Ans: 71.8 degs?
1 answer