Matt from Swindon Academy in the UK, Ambrose, Swiss and Piyush from West Island School in Hong Kong and Pete and Neha from International School of Lausanne in Switzerland found a formula for finding the areas of the triangles. Piyush said:
Area of a triangle on isometric paper = Whole number side length $\times$ other whole number side length
Pete and Neha, Matt and Ambrose used parallelograms to explain why this works. This is Ambrose's work:
For every triangle with at least two whole number sides, you can always form a parallelogram by putting 2 triangles together.
Then, from the task, “Isometric Areas”, we know that the area of a parallelogram in “$T$” is $base\times height\times2$.
For the area of a triangle, we can divide this by $2$
So the formula is: $base\times height$.
Matt thought about using small parallelograms, or 'squares', as units:
Swiss also thought about using little parallelograms as 1 unit of area:
To find the area of a normal triangle, the formula is b $\times$ h $\div$ 2 but since we're trying to find number of Triangles, you don't need to divide by 2 because 2$T$=1 unit of area.