## anonymous 4 years ago Can someone help me with Geo Problem! Diagonal AC divides a trapezoid ABCD two similar triangles ABC and ACD. Find AC if BC=4cm and AD=9cm

1. anonymous

@ganeshie8 I need help

2. anonymous

@ghazi @lalaly @AccessDenied

3. anonymous

Are these triangles similar by area?

4. anonymous

Is not there any fig. for this?

5. campbell_st

I think it looks like this|dw:1356206771435:dw| the angles marked x are equal by alternate angles in parallel lines

6. Ghazi

|dw:1356207039082:dw|

7. anonymous

Now what do i do?

8. Ghazi

have you provided whole information?

9. anonymous

yes

10. anonymous

I think there is something we r missing..

11. campbell_st

well the corresponding sides in the triangles are triangle ABC and triangle ACD are AB AC AB DC BC AD now you need to use the ratio's of corresponding sides in similar triangles

12. anonymous

but ques. does'nt say that it divides the triangles in equal areas!

13. anonymous

that's wat i was confirming earlier

14. anonymous

15. anonymous

SIMILARITY CAN ONLY BE USED WHEN AREAS ARE EQUAL

16. campbell_st

oops corresponding side should be AC and DC so using the ratio of corresponding sides $\frac{4}{9} = \frac{AB}{AC}= \frac{AC}{ DC}$

17. anonymous

what happens next?

18. anonymous

@campbell_st

19. campbell_st

who knows.... it doesn't make sense to me... there seems to be something missing from the question.

20. campbell_st

Oh, and triangles can be similar and have different areas the ratio will be the linear ratio squared. so the ratio of areas in the triangles is ABC:ACD = (4/9)^2

21. anonymous

@ghazi is there missing info?

22. Ghazi

i am confused

23. anonymous