Triangle Area
Triangle Area
Explore the area of a triangle with this free interactive math manipulative. Drag the corners to create different triangles and see how the base, perpendicular height, and area change together. The square grid and dashed enclosing rectangle help students connect the shape to the formula: area = ½ × base × height.
How to Use Triangle Area
Drag any dotted circle to move a corner. Release it to snap to a grid point. Read the base and height measurements, and use Show Area to hide or reveal the calculation. The right-angle marker shows that height is measured perpendicular to the base, rather than along a sloping side.
Explore Base, Height, and Area
Start with a horizontal base and move the top corner sideways while keeping its height unchanged. What happens to the area? Then move the corner higher or lower and compare the results. When the top corner lies above the base, the triangle occupies half of the rectangle with the same base and height.
Triangle Area supports geometry lessons, classroom demonstrations, and independent exploration of square units and the triangle area formula.
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