If cos A (cos A - 1) = 0; the measure of angle A is :

1. 90° or 0°

2. 90° and 0°

3. 45° or 90°

4. 45° and 90°

If tan⁴ A - 1 = 0 and angle A is acute, then A is :

1. 30°

2. 45°

3. ± 45°

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 sin A = 1