Of all the areas

Can you find a general rule for finding the areas of equilateral triangles drawn on an isometric grid?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Of All the Areas printable sheet

You may wish to print off some isometric paper or use the isometric dotty grid environment for this problem.

This problem follows on from Isometric Areas and More Isometric Areas.

When working on an isometric grid, we can measure areas in terms of equilateral triangles instead of squares.

 

Here are some equilateral triangles.

Image
Of all the areas


If the area of the smallest triangle is 1 unit, what are the areas of the other triangles?

Can you see a relationship between the area and the length of the base of each triangle?

Will the pattern continue?

Can you explain why?


All the triangles in the first image had horizontal bases, but it is also possible to draw "tilted" equilateral triangles.

Image
Of all the areas


These triangles all have a "tilt" of 1.

Can you convince yourself that they are equilateral?

Can you find their areas?

Take a look at the hint for ideas on how to get started.

Can you find a rule to work out the area of any equilateral triangle with a "tilt" of 1?

Can you explain why your rule works?

What about areas of triangles with a "tilt" of 2?

What about areas of triangles with other "tilts"?