If A = B = 45°, show that :
cos (A + B) = cos A cos B - sin A sin B
7 Likes
Answered By
5 Likes
If A = 30°, then prove that :
sin 3A = 3 sin A - 4 sin3 A
sin (A - B) = sin A cos B - cos A sin B
If 2sin A - 1 = 0 and A is an acute angle, the measure of angle A is :
30°
45°
60°
90°
If cos A (cos A - 1) = 0; the measure of angle A is :
90° or 0°
90° and 0°
45° or 90°
45° and 90°