Question

1. The sine of twice an angle is square root (2)/2. If the angle is between 0 and 2pie, what are its possible values?

2. The radius of a circle is increased by 20%. What is the percent increase in area?

Answer 1

The angles with a sine of (sqrt 2)/2 is 45 degrees or 135 degrees, or 360 degrees plus those angles (405 deg; 495 deg.). Your unknown angles are half of thuse angles.