Optimizing Ferris Wheel Height: Solving with Transformed Sine Function

[Veronica_Oles]

Homework Statement

The Ferris wheel at a carnival has a diameter of 18m and descends to 2m above the
ground at its lowest point. Assume that a rider enters a car at this point and rides the wheel
for two revolutions

(A) model the riders height above the ground vs the angle of rotation using a transformed sime function.

Homework Equations

The Attempt at a Solution

I know the answer is y= 9 sin (x-90) + 11

I know the a is 9 because the 18/2 and the c value is 11 because 2 + 9 = 11 but I don't know how they got to (x - 90)

 

[andrewkirk]

You need the wheel to be at its lowest point when the person gets in, which is when $x=0$. So you need the formula to be at a minimum when $x=0$. What is the minimum value of the sine function, and at what angles does it occur?

[Note: The 90 must be 90 degrees for the answer to be correct]