anonymous one year ago *

1. anonymous

@jim_thompson5910

2. anonymous

3. jim_thompson5910

your part 1 is correct, but part 2 is not

4. jim_thompson5910

|dw:1435541483644:dw|

5. jim_thompson5910

|dw:1435541514136:dw|

6. jim_thompson5910

|dw:1435541555572:dw|

7. jim_thompson5910

The period T is found through the formula T = 2pi/B

8. jim_thompson5910

do you see how to find T?

9. anonymous

no not really

10. jim_thompson5910

If you're stuck, then $\Large T = \frac{2\pi}{B}$ $\Large T = \frac{2\pi}{\frac{\pi}{15}}$ $\Large T = \frac{\frac{2\pi}{1}}{\frac{\pi}{15}}$ $\Large T = \frac{2\pi}{1}\times\frac{15}{\pi}$ $\Large T = ??$

11. anonymous

t=30pi/pi???

12. jim_thompson5910

the pi's will cancel

13. anonymous

so 30

14. jim_thompson5910

yep, the period is 30 seconds that means it takes 30 seconds for the wheel to do one full cycle

15. jim_thompson5910

in part 1, you should NOT have cos/( it should be cos( there is no division sign between the "cos" and the opening parenthesis

16. jim_thompson5910

I noticed that just now. But everything else in part 1 looks good

17. anonymous

can i do part three and you check?

18. jim_thompson5910

sure

19. anonymous

actually can you help because i have no idea where to start..

20. jim_thompson5910

we can graph the h(t) function using desmos. That's probably the easiest way an alternative is to remember that cos(x) has a min of -1. That's the smallest output cosine can give

21. jim_thompson5910

since the smallest output is -1, you can replace the cos(pi/15t) with -1 and evaluate

22. anonymous

so itd be cos((pi/15)-1)? orrrr

23. anonymous

20cos((pi/15)-1)+30?

24. jim_thompson5910

$\Large 20*\cos\left(\frac{\pi}{15}t\right) + 30$ $\Large 20*(-1) + 30 = ??$

25. jim_thompson5910

I replaced all of the cosine with -1

26. anonymous

hang on ill brb i have to take my dog out

27. jim_thompson5910

ok

28. anonymous

okay back lemme look

29. anonymous

870?

30. anonymous

or 49? do you add -1 to 30 and then add 20 or?

31. anonymous

PEMDAS so multiply then add so 20*-1 -20+30=10

32. jim_thompson5910

20(-1)+30 = 10, yes

33. jim_thompson5910

that means the lowest on the Ferris wheel is 10 ft off the ground

34. anonymous

Thank you!

35. jim_thompson5910

no problem