Question

cos(90-A) =0, then sin(A+B) =​

Answer 1

Answer :-

• sin(A + B) = cos A. sin B

Step-by-step explanation:

Given : cos(90 - A) = 0

To find : sin(A + B)

Solution :

We know that cos(90 - A) = sinA, this implies that sin A is also equal to 0.

[sin A = 0]

Now we have formula for sin(A + B) :-

sin(A + B) = sin A . cos B + cos A . sin B

>> Substitute sin A = 0

sin(A + B) = 0. (cos B) + cos A . sin B

sin(A + B) = 0 + cos A. sin B

sin(A + B) = cos A. sin B

So the required answer is cos A. sin B

More formulae :-

• sin (-x) = - sin x

• cos (-x) = cos x

• sin A = 1 / cosec A

• cos A = 1 / sec A

• tan A = 1 / cot A

• sin(A - B) = sin A.cos B - cos A . sin B

• cos(A + B) = cos A. cos B - sin A. sin B

• cos(A - B) = cos A. cos B + sin A. sin B

• sin² A + cos² A = 1

• 1 + tan² A = sec² A

• 1 + cot² A = cosec² A