Dotty triangles
Problem
Can you draw triangles of area 1, 2, 3, ?.. square
units?
Can you draw a triangle with an area of 1.5 square units?
What is the area of the smallest triangle you can draw? Is this triangle unique?
How many triangles of of area 2 square units can you draw and can you create "families" or "groups" of these triangles?
Getting Started
Look at the Shear Magic on the Prime site
Student Solutions
Solutions received gave part of an insight into the problem but ommitted to consider triangles on the dotty grid that do not have a base of whole unit length. It is possible to draw triangles whose bases and heights are neither horizontal or vertical. These triangles have bases that are not a whole number or units. A complete solution needs to consider these.
Here is a synopsis of the solutions offered for the cases considered so far (i.e. it does not consider triangles that have non-horizontal bases):
The smallest triangle it is possibkle to draw has a base of 1 unit and a height of 1 unit. So the smallest area is $ \frac{1}{2} $ sq. unit.
There are an infinite number of triangles that can be drawn with these diagonals (see the problem "Shear Magic" )There are two ways of creating a triangle of area 1 sq and with a horizontal base:
Base 1 unit; height 2 units
or
Base 2 units and height 1 unit, again
For an area of 2 sq units there are three families of triangles with a hoirizontal base::
Base 1 unit and height 4 units
or
Base 2 units and height 2 units
or
Base 4 units and height 1 unit
For each family there are an infinite number of triangles