Problem Set 48 – Perimeter of FiguresClass 5 Maths · Chapter 12 Perimeter and Area · Problem Set 48 – Maharashtra Board

Summary: Problem Set 48 – Perimeter of Figures

Only a closed figure has a perimeter. The perimeter is the total length of all its sides.

To find it, walk round the figure in your head and add every side once.

In a rectangle, opposite sides are equal, so a 9 cm by 6 cm rectangle has sides 9, 6, 9 and 6 cm: perimeter 30 cm.

In a square, all four sides are equal: a square of side 7 cm has perimeter 7 + 7 + 7 + 7 = 28 cm.

For a triangle or any odd shape, just add all the sides. Cutting a small square from a corner of a square does not change its perimeter.

Key points to remember

• Perimeter = sum of the lengths of all the sides
• Only closed figures have a perimeter
• Rectangle: opposite sides are equal
• Square: all four sides are equal
• Triangle: add its three sides
• Count every side once — do not miss short sides
• The answer has a length unit (cm, m)
• A corner notch can keep the perimeter the same

Problem Set 48 – Perimeter of Figures – Notes

1. What is perimeter?

• Perimeter is the distance all the way round the edge of a closed figure.
• Think of an ant walking along the border of a shape and coming back to where it started — the distance it walks is the perimeter.
• It is measured in units of length like cm or m.

2. Rectangles and squares

• If only two sides next to each other (adjacent sides) are given, use the fact that opposite sides are equal.
• Rectangle 9 cm and 6 cm: 9 + 6 + 9 + 6 = 30 cm.
• Square of side 7 cm: 7 + 7 + 7 + 7 = 28 cm.

3. Triangles

• A triangle has three sides. Add them.
• Sides 5 cm, 7 cm and 9 cm: 5 + 7 + 9 = 21 cm.
• If all three sides are 6 cm, the perimeter is 6 + 6 + 6 = 18 cm.

4. Figures with many sides

• Mark a starting corner and go round, writing each side's length.
• Tick each side as you add it so you do not count it twice or skip it.

5. Cutting a corner from a square

• Take a square of side 4 cm and cut a 1 cm square from one corner.
• Two pieces of 1 cm are lost from the outer edge, but two new edges of 1 cm appear inside the notch.
• So the perimeter stays 4 × 4 = 16 cm, even though the shape has become smaller.

Formulas at a glance

Key terms

Problem Set 48 – Perimeter of Figures – Flashcards

Read the question, answer it in your head, then tap the card to check. 10 cards.

Problem Set 48 – Perimeter of Figures – MCQ Quiz

10 questions. Tap an option — you will see at once if it is right and why.

How to study Problem Set 48 – Perimeter of Figures

⏱ About 20 minutes

1. Learn (5 min)
   Understand perimeter as the walk round the edge of a closed figure.
2. Measure (10 min)
   Measure the sides of a book, a notebook and a tile and find each perimeter.
3. Practise (5 min)
   Do the 4 'Try it yourself' sums, take the quiz and play 🎮 Play.