Question

find the value of sin-¹[sin 4π/3]

Answer 1

1. Convert radians to degrees: (4π/3) × (180/π)= 240º
2. 240º is in the 3rd quadrant, so we subtract 180 to get the reference angle: 240–180= 60º.
3. Based on 30–60–90 right triangle, the sin of 60º= √3/2.
4. Because 240º is in the 3rd quadrant, the sin is negative.