Question

1. sin(A + B) sin(A-B)
=​

Answer 1

(a+b) (a- b)= (a square-b square

Answer 2

sin(A+B).sin(A−B)
=[sin(A)cos(B)+cos(A)sin(B)][sin(A)cos(B)−cos(A)sin(B)]
=sin
2
Acos
2
A−cos
2
Asin
2
A
=sin
2
A[1−sin
2
B]−[1−sin
2
A]sin
2
B
=sin
2
A−sin
2
Asin
2
B−sin
2
B+sin
2
Asin
2
B
=sin
2
A−sin
2
B
Hence,theoptionCisthecorrectanswer.
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