## ksaimouli 3 years ago a woman 5 feet tall is walking away from a streetlight hung 20 feet from the ground at a rate of 6ft how fast the shadow lengthing

1. ksaimouli

|dw:1353865196344:dw|

2. ksaimouli

beside 5 is 20

3. ksaimouli

i just want

4. ksaimouli

similar triangle

5. ksaimouli

can i use |dw:1353865365236:dw|

6. ksaimouli

@hartnn

7. asnaseer

you are using exactly the right approach. find x in terms of y and then differentiate with respect to time to get your answer.

8. ksaimouli

i know i got 18 but book used another one |dw:1353865556968:dw|

9. ksaimouli

which is right way

10. ksaimouli

they got 2ft/sec

11. asnaseer

I think you have an error in your calculation. If I use the same ratio as you showed initially then I get an answer of 2 ft/s

12. ksaimouli

hmmm

13. asnaseer

14. ksaimouli

|dw:1353865761171:dw|

15. ksaimouli

|dw:1353865816040:dw|

16. ksaimouli

dx/dt=6

17. asnaseer

sorry I meant that you have been given dy/dt = 6

18. asnaseer

19. ksaimouli

so the shadow falls in front of her because the light is backwards?

20. asnaseer

yes - but I would say the light is behind her rather than "backwards" :)

21. ksaimouli

thx becasue of silly mistake whole answer is wrong thx for correcting me

22. asnaseer

yw :)