Master rectangle properties, formulas, and applications. Learn why rectangles are everywhere in our daily lives and how to solve practical problems.
A rectangle is a parallelogram with one right angle (which makes all four angles right angles). It's also called a quadrilateral because it has four sides and four vertices.
Since opposite sides are parallel and all angles are 90°, rectangles are some of the most useful and stable shapes in construction and design.
Each interior angle is exactly 90°
Length and width pairs are equal
Like all parallelograms
Cross at the center, equal length
P = 2 × (a + b)
Where a is the length and b is the width
Example: Rectangle with length 8 and width 5 → P = 2 × (8 + 5) = 26 units
A = a × b
Where a is the length and b is the width
Example: Rectangle with length 8 and width 5 → A = 8 × 5 = 40 square units
Students often mix up which dimension is length vs. width when calculating perimeter.
✅ Solution: Remember: it doesn't matter which you call length or width, just be consistent in your calculation.
When calculating perimeter, students sometimes use length + width instead of 2 × (length + width).
✅ Solution: Visualize the rectangle: there are TWO lengths and TWO widths that make up the perimeter.
In real-world problems, forgetting to account for walls when calculating fencing or materials needed.
✅ Solution: If one or more sides are against a wall, subtract those sides from the perimeter calculation.
Phone screens are rectangular to maximize viewing area while maintaining structural integrity and ease of manufacturing.
Soccer/football fields are rectangular providing equal playing conditions for both teams with clear boundaries.
Book pages are rectangular for optimal text layout, easy reading, and efficient paper usage in printing.
Test your understanding with interactive rectangle calculators and problem-solving tools.
Explore more quadrilateral shapes and their unique properties.