## itsonlycdeee Group Title The equation below gives the height h of a passenger on a Ferris wheel at any time t during the ride to be h = 137 − 122 cos (π/10)t where h is given in feet and t is given in minutes. Use this equation to find the times at which a passenger will be 120 feet above the ground during the first revolution. I found the first time, which is about 4.5, but I'm confused on how to find the second time. one year ago one year ago

1. robz8

are you familiar with the unit circle? the are 2 quadrants in the unit circle which cos(t) is positive

2. itsonlycdeee

Yes, the 1st quadrant and the 4th quadrant.

3. robz8

is t inside or outside of the cos?

4. itsonlycdeee

Outside

5. primeralph

Should be inside.

6. primeralph

Well, most likely.

7. robz8

are you sure?, because then h = 137 − 122 cos (π/10)t would be linear, meaning there is only 1 time h = 120

8. itsonlycdeee

Oh, then inside does make more sense.

9. robz8

120 = 137 − 122 cos (π/10*t) -17 = -112 cos(π/10*t) 17/112 = cos(pi/10*t) $\cos^{-1} (17/112) = \frac{ \pi }{ 10 }t$

10. itsonlycdeee

Thank you I just figured it out!