Find a, b, and c...3

[nycmathguy]

Section 4.5

Question 69

Let a = 3 = amplitude

Let b = period

b = (2pi)/(3pi/2 - pi/4)

b = 8/5

Let c = phase shift = pi/2

Our equation is f(x) = 3 sin(8x/5 - pi/2).

You say?

 

[MathLover1]

b = (2pi)/(3pi/2 - pi/4)

one full oscillation is distance from -pi/4 to 3pi/4 which is 4pi/4=pi
b = (2pi)/pi
b=2
phase shift c= pi

f(x) = 3 sin(2x - pi)

 

[nycmathguy]

b = (2pi)/(3pi/2 - pi/4)

one full oscillation is distance from -pi/4 to 3pi/4 which is 4pi/4=pi
b = (2pi)/pi
b=2
phase shift c= pi

f(x) = 3 sin(2x - pi)

Again, how do you find b? How do you know that b is 2?