Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2006-02-28 15:30:27

naturewild
Member
Registered: 2005-12-04
Posts: 30

Similar triangles

This question is really easy but I'm weak in similar triangle.. I dont know how to do it.

In triangle ABC, D and E are in AB and AC respectively such that DE is parallel to BC, AD = 3, DB = 4, and triangle ADE = 81. Determine

1. triangle ABC

2. quadrilateral DBCE

Offline

#2 2006-02-28 15:49:03

mikau
Member
Registered: 2005-08-22
Posts: 1,504

Re: Similar triangles

triangle ADE = 81 makes no sense. Do you mean ADE = 81 degrees or something?


A logarithm is just a misspelled algorithm.

Offline

#3 2006-02-28 15:55:46

naturewild
Member
Registered: 2005-12-04
Posts: 30

Re: Similar triangles

oh those are the areas I mean.

Offline

#4 2006-02-28 18:03:57

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,908

Re: Similar triangles

S[ade]:S[abc]=3:7
S[dbce]=S[abc]-S[ade]
So you can do it all alone.


IPBLE:  Increasing Performance By Lowering Expectations.

Offline

#5 2006-02-28 18:14:48

naturewild
Member
Registered: 2005-12-04
Posts: 30

Re: Similar triangles

I tried doing it that way. Let's say x = triangle ABC

ADE / ABC = 3 / 7

81/x = 3/7

x = 189

But the answer is 441

Offline

#6 2006-03-01 06:57:42

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,582

Re: Similar triangles

Did you say that D is along AB and E is along BC?
If so, then DE is parallel to AC, not BC.


igloo myrtilles fourmis

Offline

#7 2006-03-02 20:45:01

boyhuesd
Member
Registered: 2006-03-02
Posts: 1

Re: Similar triangles

o!
It very easy!
ec! ec!

Offline

Board footer

Powered by FluxBB