Question

4. If A = 30°, and B = 60°, verify that:
(ii) cos (A + B) = cos A cos B - sin A sin B​

Answer 1

Answer:

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Step-by-step explanation:

=> cos(A+B) = cos A cos B - sin A sin B

=> cos (30+60)°= cos30° cos60°- sin 30° sin60°

=> cos 90° = 1/2*√3/2 - √3/2*1/2

=> 0 = √3/4 - √3/4

=> 0= 0

=> LHS = RHS

Hence, proved