Question

If sinA=4/5and cosB=-5/13 where 0<A<π/2,I/2<B<I.Find the value cos(A-B)​

Answer 1

Answer:

As we know that cos (A - B) = cos A cos B + sin A sin B Therefore, cos (A - B) = cos A cos B + sin A sin B = 3/5 × 5/13 + 4/5 × 12/13 = 15/65 + 48/65 = 63/65

Answer 2

Step-by-step explanation:

• sinsquareA+cossquareA=1. (sinA=4/5). so cos A =3/5. (cos B=5/13). so. sin B=12/13 . We know cos (A-B) = (cos A×. cos B )+(sin A × sin B) ...we get sin B & cos A .... applying this we get the answer is .= 63/65 .........