MENUTriangle Area Puzzles
On each grid, connect three dots to make a triangle with the given area. Each small square has an area of 1. Click three dots and a mark shows if your triangle is right. Click a dot again to take it back. Reload the page for 12 new puzzles.
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How to find the area of a triangle on a grid
The area of a triangle is half of base times height: ${A = \dfrac{b \cdot h}{2}}$. Each small square of the grid has area 1.
Example 1: a side on a grid line
The bottom side lies on a grid line, so it is the base: ${b = 2}$. The top dot is 3 squares above that line, so ${h = 3}$ and ${A = \dfrac{2 \cdot 3}{2} = 3}$.
Example 2: no side on a grid line
- Draw the smallest rectangle around the triangle along the grid lines. It is 3 by 2, so its area is ${3 \cdot 2 = 6}$.
- Three right triangles are left at the corners of the rectangle. Their areas are ${\dfrac{3 \cdot 1}{2} = 1.5}$, ${\dfrac{1 \cdot 1}{2} = 0.5}$ and ${\dfrac{2 \cdot 2}{2} = 2}$.
- Subtract them from the rectangle: ${6 - 1.5 - 0.5 - 2 = 2}$.
A triangle with its corners on the dots of a grid always has an area that is a whole number or a whole number and a half.
More about areas: Area of a Triangle.
Area