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Area Formulas for 2D Shapes
Chart
grade 5
English
Area Formulas for 2D Shapes
Area Formulas for 2D Shapes
Area is the amount of space inside a two-dimensional shape. It is measured in square units, such as square centimeters
or square meters
.
1. Parallelograms
A parallelogram is a quadrilateral with two pairs of parallel sides. To find its area, we use the base (b) and the height (h).
The Formula
- Base (b): Any side of the parallelogram.
- Height (h): The perpendicular distance from the base to the opposite side.
Tip: The height is always at a right angle (90°) to the base!
2. Triangles
A triangle's area is exactly half of a parallelogram with the same base and height.
The Formula
Identifying Height in Different Orientations
The height of a triangle can be found inside, outside, or as a side of the triangle, depending on the type of triangle.
Height Inside
In acute triangles, the height is often found inside the shape.
Height Outside
In obtuse triangles, you may need to extend the base to find the perpendicular height.
3. Trapezoids
A trapezoid is a quadrilateral with at least one pair of parallel sides. These parallel sides are called bases (
and
).The Formula
4. Estimating Area Using Grids
When a shape is on a grid, you can estimate its area by counting the unit squares.
- Count Full Squares: Count every square that is completely inside the shape.
- Combine Partial Squares: Two half-squares can be counted as 1 full square. For smaller pieces, estimate if they add up to a whole.
Example: In the triangle above, count the full grid squares first, then combine the partial squares along the edges to estimate the total area in square units.