Question

Determine an equivalent expression for sin 3x cos x + cos 3x sin x

Answer 1

sin(A-B) = sinAcosB - cosAsinB

A = 3x
B = x

sin(3x-x) = 0
sin(2x) = 0
2x = nπ
x = nπ/2 where n is an integer

Answer 2

sin(4x)

Answer 3

Have a look at this page: http://en.wikipedia.org/wiki/List_of_trigonometric_identities#Angle_sum_and_difference_identities

Answer 4

sin(3x - x)
sin(a-b) = sinacosb -cosbsina

Answer 5

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Answer 6

sin 4x = sin(3x+x) = sin 3x cos x + cos 3x sin x

sin 4x

Answer 7

I should have read the original problem
it is sin(a + b). jimmyrep is correct