Perimeter and Area of Polygons
Selected Reading
- Finding the perimeter or area of a rectangle in the coordinate plane
- Area of a trapezoid
- Area of a parallelogram
- Area involving rectangles and triangles
- Finding the area of a trapezoid on a grid by using triangles and rectangles
- Area of a triangle
- Finding the area of a right triangle or its corresponding rectangle
- Finding the area of a right triangle on a grid
- Area between two rectangles
- Area of a piecewise rectangular figure
- Finding the side length of a rectangle given its perimeter or area
- Word problem involving the area of a square or a rectangle
- Areas of rectangles with the same perimeter
- Distinguishing between the area and perimeter of a rectangle
- Area of a rectangle involving fractions
- Perimeter of a piecewise rectangular figure
- Finding the missing length in a figure
- Sides of polygons having the same perimeter
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Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
Area involving rectangles and triangles
Area involving rectangles and triangles
In this lesson we solve problems involving rectangles and triangles. We are given rectangles. In these rectangles, triangles are drawn or cut off and the remaining area or area between rectangle and triangle is to found.
a. For example we have a rectangle and triangle as follows
We are required to find the area between the rectangle and the triangle
Area of shaded region = Area of rectangle – Area of triangle
b. For example we have a triangle cut off from a rectangle as follows
We are required to find the area of the remaining part of the rectangle which is shaded.
Area of shaded region = Area of rectangle – Area of triangle
Find the area of the shaded region in the following figure.
Solution
Step 1:
Area of rectangle = l × w = 8 × 6 = 48 sq m; Area of triangle = $frac{1}{2}$ b h = $frac{1}{2}$ × 6 × 4 = 12 sq m
Step 2:
Area of shaded region = Area of rectangle – Area of triangle
= 48 – 12
= 36 square m
Find the area of the shaded region in the following figure.
Solution
Step 1:
Area of rectangle = l × w = 8 × 5 = 40 sq ft; Area of triangle = $frac{1}{2}$ b h = $frac{1}{2}$ × 4 × 3 = 6 sq ft
Step 2:
Area of shaded region = Area of rectangle – Area of triangle
= 40 – 6
= 34 square ft