Question

sin(A+B)cos(A-B)+sin(A-B)cos(A+B)=sin 2a​

Answer 1

Answer:

let A+ B = X

and. A-B. = Y

ASKED

= sinX.cosY+cosX.sinY

=sin(x+y)

= Sin(2A)

Answer 2

Answer:

LHS_

• (sinA cosB + cosA sinB)(cosA cosB+sinA sinB) + (sinA cosB - cosA sinB)(cosA cosB - sinA sinB)
• sinA cosA + sinA cosA
• 2sinA cosA

RHS_

• sin2A
• sin(A+A)
• sinA cosA +sinA cosA
• 2sinA cosA

Therefore, LHS=RHS

Hence, proved