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°
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cos A (cos A - 1) = 0
⇒ cos A = 0 or cos A = 1
⇒ cos A = cos 90° or cos A = cos 0°
The measure of angle A is 90° or 0°.
Hence, option 1 is the correct option.
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If A = B = 45°, show that :
cos (A + B) = cos A cos B - sin 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 tan4 A - 1 = 0 and angle A is acute, then A is :
± 45°
± 30°
If 2sin 3A - 1 = 0 ; the value of angle A is :
20°
10°