Question

2 sin 7a cos 3a is equall to ​

Answer 1

Answer:

ANSWER

sinA+sin3A+sin5A+sin7A

=2sin2AcosA+2sin6AcosA

=2[sin2A+sin6A]cosA

=2[2sin4Acos2A]cosA

=4sin4AcosAcos2A

=4cosAcos2Asin4A

Answer 2

The value of 2 sin 7 a cos 3 a is equal to sin 10 a + sin 4 a.

Step-by-step explanation:

Given:

2 sin 7 a  cos 3 a

To Find:

The value of 2 sin 7 a cos 3 a .

Formula Used:

2 sin A cos B = sin ( A+B) + sin ( A-B)  ------------------------Equation no.01

Solution:

2 sin 7 a cos 3 a

Applying the formula no. 01

2 sin 7 a cos 3 a = sin (7 a+3 a)+ sin(7 a-3 a)

                          = sin 10 a + sin 4 a

Thus, The value of 2 sin 7 a cos 3 a is equal to sin 10 a + sin 4 a.