Problem Set 28 – Radius, Chord, Diameter and Drawing CirclesClass 5 Maths · Chapter 7 Circles · Problem Set 28 – Maharashtra Board

Summary: Problem Set 28 – Radius, Chord, Diameter and Drawing Circles

The centre is the middle point of a circle. Every point on the circle is the same distance from it.

A radius joins the centre to a point on the circle. A circle has many radii, all of the same length.

A chord joins any two points on the circle.

A diameter is a chord that passes through the centre. It is the longest chord.

To draw a circle of radius 3 cm, open the compass so that the pencil point is 3 cm from the metal tip, hold the tip still and turn the pencil round.

Key points to remember

• Centre = middle point of the circle
• Radius: centre to a point on the circle
• All radii of a circle are equal
• Chord: any two points on the circle
• Diameter: a chord through the centre
• The diameter is the longest chord
• A compass draws circles
• Compass opening = radius

Problem Set 28 – Radius, Chord, Diameter and Drawing Circles – Notes

1. The centre and the radius

• Every circle has a centre. Usually we call it O or C.
• A line from the centre to any point on the circle is a radius. The plural of radius is radii.
• If O is the centre and K is on the circle, then OK is a radius. OJ, OL… are more radii, all the same length.

2. Chords

• Pick any two points on the circle and join them with a straight line. That line is a chord.
• A chord does not have to pass through the centre.
• A circle has countless chords — short ones near the edge and long ones near the middle.

3. The diameter

• A chord that goes through the centre is called a diameter.
• It cuts the circle into two equal halves.
• It is the longest chord you can draw in a circle.

4. Using a compass

• A compass has two arms. One has a sharp metal point; the other holds a pencil.
• Fix the pencil so that its tip is level with the metal point.
• Put the metal point on the paper and keep it still. Turn the pencil all the way round. The shape you get is a circle; the metal point marks the centre.

5. Drawing a circle of a given radius

• Place the metal point on the 0 mark of a ruler. Open the compass until the pencil tip is on the radius you need, say 4 cm.
• Do not change the opening. Mark a centre point on paper and draw the circle.
• Check: draw a radius and measure it with the ruler — it should be 4 cm.

Formulas at a glance

Key terms

Problem Set 28 – Radius, Chord, Diameter and Drawing Circles – Flashcards

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

Problem Set 28 – Radius, Chord, Diameter and Drawing Circles – MCQ Quiz

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

How to study Problem Set 28 – Radius, Chord, Diameter and Drawing Circles

⏱ About 25 minutes

1. Learn (5 min)
   Learn the words centre, radius, chord and diameter.
2. Draw (15 min)
   Draw circles of radius 2 cm, 3 cm and 4 cm. On one circle mark a radius, a chord and a diameter.
3. Practise (5 min)
   Do the 4 'Try it yourself' sums, take the quiz and play 🎮 Play.