graphing calculators viewing screen the graph of y 4 sin 2x

graphing calculator\'s viewing screen the graph of y = 4 sin 2x cos (-2x) would coincide with the graph of which of the following? (A) y = 2 sin 2x (B) y = 2 sin 4x (C) y = 4sin 4x (D) y = -2cos4x

Solution

Solution:

y = 4*sin(2x) cos(-2x)

As we know that cos(-x) = cos(x)

y = 4 sin(2x) cos(2x)

now Sin(2A) = 2sin(A)cos(B)

y = 2 (2sin(2x) cos(2x))

y = 2 sin(4x)

therefore option (B) is correct