Q7 of 46 Page 284

Is it right to say that sin(A + B) = Sin A + Sin B? Justify your answer.

No, it is not correct to say that sin (A + B) = sin A + sin B.

Justification: Let’s justify it by showing contradiction.


Let it be true that, sin (A + B) = sin A + sin B.


Now, let A = 30° and B = 60°


Then,


sin (30° + 60°) = sin 30° + sin 60°


sin 90° = sin 30° + sin 60°


1 = 1/2 + √3/2


1 = (1 + √3)/2


But, it’s not true.


1 ≠ (1 + √3)/2


Hence, we have a contradiction.


And therefore, it’s not right to say that sin (A + B) = sin A + sin B.


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