PLEASE HELP ME ASAP!!! I AM SO CONFUSED !!!!! i TRIED IT SEVERAL TIMES! DIDNT WO

Question

PLEASE HELP ME ASAP!!! I AM SO CONFUSED !!!!! i TRIED IT SEVERAL TIMES! DIDNT WORK i ONLY HAVE ONE MORE TRY PLEASE HELP ME!

THE FUNCTION I WAS USING WAS:

Acos(B(t-C))+D

THE WORNG ANSWERS THAT I HAVE TRIED WAS:

90.25, 39.719, 39.72, 82.25

HERE IS THE QUESTION:

Shirley is on a Ferris wheel which spins at the rate of 3.8 revolutions per minute. The wheel has a radius of 55 feet, and the center of the wheel is 67 feet above the ground. After the wheel starts moving, Shirley takes 11 seconds to reach the top of the wheel.

How high above the ground is she when the wheel has been moving for 5 minutes? (Round your answer to two decimal places.)

6, 1 17.PoC6. My Note 012 point? l Previous Answers Shirley is on ?erns wheel which spins at the rate of 3.8 revolutions per minute. The whecl has a adius of 55 feet, and the center of the wheel s 67 feet above the around. After the wheel starts moving. Shirley takes 11 seconds to rcach the top of the whecl. How high above the ground is she when the wheel has been moving for S minutes? (Round your answer to two decimal places.) 90 25 x ft Additional Materials Reading Subrrit Answer Save Progess

Explanation / Answer

Radius = 55 feet
Center is 67 ft above ground.

So, minimum height = 67 - 55 = 12

max height = 12 + 55*2 ---> max = 122

Now,
amplitude A = (max - min)/2 ---> 110/2 --> 55

D = vertical shift = (max + min)/2 --> (122 + 12)/2 ---> 67

3.8 rev per minute

So, 1 rev per 1/3.8 min

So, period = 5/19 min

And thus B = 2pi/period
becomes
B = 2pi / (5/19)

B = 2pi * 19/5

B = 38pi/5

Now, C = 0

Now, where does Shirley start?
Lets find out....

y = -55cos(38pi/5 * (t - C)) + 67

When t = 11, y = 122

So, solving for C,
-1 = cos(38pi/5 * (11 - C))

38pi/5 * (11 - C) = pi

11 - C = 5/38

C = 413/38

So, eqn becomes :
y = -55cos(38pi/5 * (t - 413/38)) + 67

Now, plug in t = 5,
we get :
y = -55cos(38pi/5 * (5 - 413/38)) + 67

84.00 -----> ANS

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