anonymous 4 years ago how do you get this length...

1. amistre64

i feel that your questions might be lacking some vital components :/

2. anonymous

|dw:1327247673332:dw|

3. amistre64

thats a scaled version of the base

4. anonymous

That's a secret length.

5. amistre64

if you knew some angles itd be doable as well

6. anonymous

I think we can use Euler straight edge for that.

7. AravindG

wt kind of triangle is it???

8. amistre64

did Fool just suggest a ruler? lol

9. anonymous

i don't need a numerical answer. length in question is c, height of c from base b is y

10. anonymous

not a right trianle

11. amistre64

|dw:1327247884124:dw|

12. anonymous

just need to solve in terms of y. no angle given

13. anonymous

^^^^yes

14. amistre64

$\frac{c}{h}=\frac{b}{h-y}$ $c=\frac{bh}{h-y}$is my only idea without knowing any fancy triangle thrms

15. amistre64

where h = height of the altitude

16. anonymous

hmmm i hate answering "none of the above"

17. amistre64

we have options?

18. anonymous

yes

19. amistre64

way to make life harder for us by not posting them, kudos :)

20. anonymous

Yes amstre that's a ruler :D

21. anonymous

a) (h-y)(b/h) b)(h-y)(h/b) c)(b/h)y d)(h/b)y

22. anonymous

sorry, i wasn't trying to get a straight answer in the first place, i want to solve :P

23. anonymous

You need to use basic proportionality theorem.

24. amistre64

i think my solution is adequate then, if we can rearrange it into one of those formats

25. amistre64

$\frac{bh}{h-y}$ $b\frac{h}{h-y}$ $b\frac{1}{1-y/h}$ maybe the wolf can give us options?

26. amistre64

it was worth a shot, check my proportion; is it ok?

27. anonymous

about to just plug in numbers and see

28. amistre64

|dw:1327248716441:dw|

29. amistre64

this is the same type of set up but with something i can see better

30. anonymous

your proportions aren't right but i also don't know if this pic is drawn to scale. h is longer than b, c is shorter than b, of coarse. and y is shorter than b and c

31. anonymous

from your expressions, c ends up being longer than b

32. amistre64

3/4 = 2/c c = 8/3 = 2 2/3? sqrt(2^2 + 8/3^2)= 10/3 5/3 = d/2 10/3 = d thats a match in my book

33. amistre64

c is to b as h-y is to h $c=\frac{b}{h}(h-y)$might be better :)

34. amistre64

i think that matches your "a" option

35. anonymous

yes, it's exact. i don't get why though. so did you derive "a" from your earilier expression c=(bh)/(h-y)?

36. amistre64

no, i had to dust out the cobwebs and make sure I was putting things in their proper places.

37. amistre64

similar triangle differ by some scalar multiple; they keep the same ratios from one tri to the next

38. amistre64

so if we equate the proper ratios we can solve for them

39. amistre64

bases with repect to heights will math in silimlar tris. b/h = c/(h-y) are the respective parts to match up

40. amistre64

then we solve for c

41. anonymous

i think i need to study "basic proportiionality theorem". don't recall learning about it

42. anonymous