Find the period range and amplitude of the cosine function y

Find the period, range and amplitude of the cosine function. y = - 4cos 8x period = 1/4, range = - 4 le y le 4, amplitude = 4 period = 1/4 pi, range = - 4 le y le 4, amplitude = 4 period = 1/2 pi, range = - 4 le y le 4, amplitude = -4 period = 1/2, range = - 4 le y le 4, amplitude = -4

Solution

y = -4cos8x

General cosine function : y = AcosBx where A = amplitude

B = 2pi/period

Amplitude = 4

Period = 2pi/8 = pi/4

Range : max amplitude = +4 and minimum -4

So, Range =[-4, 4 ]

Option B