Congruence and Similarity question

• Pfft

  6 May 09, 17:38

  ABC = AED

  Given that AD =3cm, AE = 5cm and EC = 2cm, calculate

  Area of triangle AED / Area of triangle ABC

   

   

• Forbiddensinner

  6 May 09, 18:13

  Originally posted by Pfft:

  ABC = AED

  Given that AD =3cm, AE = 5cm and EC = 2cm, calculate

  Area of triangle AED / Area of triangle ABC

   

   

  Perhaps a picture or a model will be more helpful.

  I am still trying to figure out how the whole thing looks like.

• Pfft

  6 May 09, 18:31

  

  Hope this helps

• wee_ws

  6 May 09, 18:46

  Hi,

    Since triangle ABC is similar to AED, we consider the ratio AD : AC which is 3 : 7.

    With this, I'm sure you can proceed to find ratio of their areas.

    Thanks!

  Cheers,
  Wen Shih

• Pfft

  6 May 09, 19:32

  so, If the ration of the sides is 3 : 7, the ratio of areas would be 3^2 : 7^2.

  and it'll be 9 / 49 ?

   

  Btw, when do i use this formula? A1 / A2 = (b1 / b2)^2 ?

• wee_ws

  6 May 09, 19:39

  Originally posted by Pfft:

  so, If the ration of the sides is 3 : 7, the ratio of areas would be 3^2 : 7^2.

  and it'll be 9 / 49 ?

   

  Btw, when do i use this formula? A1 / A2 = (b1 / b2)^2 ?

  Hi,

    Good.

    When you need to compare areas of similar figures, like in the question we saw.

    Thanks!

  Cheers,
  Wen Shih