PERIMETER
Definition Of Perimeter
Perimeter is the distance around a polygon.
Examples of Perimeter
The perimeter of the rectangle shown is AB + BC + CD + DA = 8 + 5 + 8 + 5 = 26 units
.
Perimeter of a rectangle can also be found using the formula 2(l + w), where l is the length and w is the width.
Video Examples: Perimeter - MathHelp.com - Math Help
Solved Example on Perimeter
Ques: ABC is an equilateral triangle and the perimeter of triangle ABC is 12 in. Find the measure of each side.
Choices:
A. 36 in.
B. 4 in.
C. 12 in.
D. 6 in.
Correct Answer: B
Solution:
Step 1: In triangle ABC, AB = BC = CA
Step 2: Let AB = BC = CA = x in.
Step 3: Perimeter of รขโยณABC = AB + BC + CA
Step 4: AB + BC + CA = 12
Step 5: x + x + x = 12 [Substitute AB = BC = CA = x.]
Step 6: 3x = 12 [Combine like terms.]
Step 7: [Divide each side by 3.]
Step 8: x = 4 [Simplify.]
Step 9: AB = BC = CA = 4 in.
Step 10: So, the measure of each side is 4 in.
Quick Summary
- Perimeter is the total length of all the sides of a shape.
- To find the perimeter, add up the lengths of all the sides.
๐ Teacher Insights
Use hands-on activities, like measuring the perimeter of the classroom or schoolyard, to reinforce the concept.๐ Prerequisites
- Addition
- Basic shapes (squares, rectangles, triangles)
- Understanding of units of measurement
Check Your Knowledge
Q1: What is the perimeter of a rectangle with length 8 and width 5?
Q2: An equilateral triangle has a perimeter of 12. What is the length of each side?
Frequently Asked Questions
Q: What is a polygon?
A: A polygon is a closed 2D shape with straight sides.
Q: How do I find the perimeter of a circle?
A: The perimeter of a circle is called the circumference, and you find it using the formula C = 2ฯr, where r is the radius.