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More Triangles on Geoboards

Check out this blue Isosceles triangle.

To find out the area of this blue triangle we could (and will eventually) use the standard formula.  But first let’s do some cool stuff!

Let’s figure out the area of the rectangle that triangle is in.  Easy, right?  The area of the rectangle is 8.

Or maybe I might want to look at it this way.  Now I’ve spliced the blue triangle in half.  I can see that I’ve ended up creating four congruent right triangles.

Now I have a lot of information.

If I wanted to, I could even turn this into an algebra problem.

Y + Y + B = 8

B = Y +Y

Y + Y + Y + Y = 8

2 = 8

B = 2 + 2

Or, I could go back to the traditional formula.

area of the blue triangle = 1/2(2 X 4) = 4

Geometry, multiplication, fractions and algebra all in one lesson?

Yup!  Geoboards are awesome.

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