Math Is Fun Forum

mathgirl1997

Member

Registered: 2010-12-11

Posts: 12

Area of right triangle

Hi! I haven't used the forum in a while but i'd like some help.

right Triangle #1 has an area of fifteen and a base of 6. Right triangle #2 has a base of 12 but what is the area?

---

"Dowell...not because its easy but because its hard "-JFK adapted by Dowell Middle School
Sincerely FSRZ <3

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Area of right triangle

Hi mathgirl1997;

Are the heights of the two triangles the same?

Otherwise all I can say is that the area of the second triangle is

A = 6h

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,583

Re: Area of right triangle

hi mathgirl1997

I'm guessing that there's another bit of information here;  the triangles are similar.

If that's right then length scale factor is x 2 so the area scale factor is x 4 => new area = 15 x 4 = 60.

Later edit:

I've thought some more and I think you have a diagram like the one at the bottom of this post.

The letters may be different and the dotted lines definitely won't be there but other than that, is this your problem?

ABC and ADE are said to be similar triangles.  In maths that means ADE is an exact enlargement of ABC.

As the base has doubled, so has the height.  But the area goes up by a factor of x4.

I have put on the dotted lines to make that clear.  You can fit 4 copies of ABC into the space ADE.

Bob

Last edited by Bob (2011-02-11 01:28:14)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob