If 2sin 3A - 1 = 0 ; the value of angle A is :

1. 20°

2. 60°

3. 10°

4. 30°

If 3tan² A - 1 = 0 and angle A is acute, the measure of angle A is :

1. 20°

2. 45°

3. 60°

4. 30°

Solve the following equations for A, if :

2 cos 2 A = 1