## Best_Mathematician 2 years ago calculus help...last two questions...

1. Best_Mathematician
2. Best_Mathematician

@electrokid can u help me with last two

3. electrokid

how were you able to solve the first ones? You have to picture it and draw it first. Just a little bit of imagination gives the answer right away.

4. FibonacciChick666

so you got the first three right? now you want a function that shows \[2[ \mathsf { {r}}(t)]\] So what was our original r(t)

5. FibonacciChick666

btw this isn't dif eq

6. Best_Mathematician

r(t) = (t-sint)i + (1-cost)j so if it is 2[r(t)] = (2t-2sint)i + (2-2cost)j is it correct?

7. Cummins5-9

i am not smart

8. Best_Mathematician

@electrokid is this what you talking about? |dw:1367589459350:dw| i got this part but what abt rest part @FibonacciChick666 r(t) = (t-sint)i + (1-cost)j so if it is 2[r(t)] = (2t-2sint)i + (2-2cost)j is it correct?

9. electrokid

|dw:1367594323679:dw| this is the diagram I was talking about

10. Best_Mathematician

how does this diagram relates with vectors

11. electrokid

|dw:1367594594073:dw| r(t) is the position vector of that small balck strip

12. Best_Mathematician

oh gotcha...so circumference is the vector function that models the behavior

13. electrokid

r(t) is the vector function linear distance travelled is easier to analyse by considering curcumference distances

14. electrokid

r(t) is the position of that small strip on the bigger loop with radius R "r" = radius of smaller loop (confusing symbol, so use another one maybe "a" find a relation between R and "a"

15. Best_Mathematician

R = 2r....?

16. electrokid

then what is the relation between "r(t)" and R?

17. Best_Mathematician

r(t) = 4piR...?

18. Best_Mathematician

wait r(t) = 2R...correct?

19. electrokid

20. Best_Mathematician

wow...how did u do that

21. electrokid

never mind how. but do you see how the question works?

22. electrokid

I'll let @FibonacciChick666 continue from here

23. Best_Mathematician

ya circumference is equal to 2pi. It takes 6seconds approx for that circle to complete one revolution