
Thien D. answered 07/08/19
Tutor
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Duke MS Engineering Grad For Math Tutoring
The product identity states that:
sin(a)cos(b) = 0.5[sin(a+b) + sin(a-b)]
Using this identity, we can plug in "a" and "b":
sin(7x)cos(4x) = 0.5[sin(7x + 4x) + sin(7x - 4x)]
= 0.5[sin(11x) + sin(3x)]