Class 5 Exam  >  Class 5 Notes  >  Mathematics for Class 5  >  Chapter Notes: Circles

Circles Class 5 Notes Maths

Have you ever noticed the wheels of your bicycle, the round face of a clock, or a yummy pizza? All of these things have something in common—they are circles! 
Circles Class 5 Notes Maths

In this chapter, we will explore the magical world of circles. Get ready to have some fun while learning!

Circle

  • A circle can be defined as a simple closed curve all of which points are equidistant (at an equal distance) from the fixed point called its centre.
  • A bangle, a one-rupee coin and a cycle tyre are all examples of circular objects.

Circles Class 5 Notes Maths

1. Centre

The fixed point in the centre of a circle is called its centre

2. Diameter

  • A Diameter is a line segment with endpoints on the circle that passes through the centre.
  • In the picture given below, 
    the Diameter = AB
    AB = (OA + OB) = 2 × OA or 2 × OB
    Circles Class 5 Notes Maths
  • The Radius is half of the Diameter.
    Radius = (Diameter)/2
  • This also implies that Diameter = 2 x Radius

3. Radius

  • Radius is the distance between the centre of a circle and a point on the circumference.
  • In the picture given below, the Radius = OA = OBCircles Class 5 Notes Maths

4. Chord

  • A chord is a line segment whose endpoints lie on the circle.
  • LM, PQ, and AB are all chords of the circle. 
  • The Diameter is the longest chord of the circle.

Circles Class 5 Notes Maths

5. Arc

  •  Arc is any part of a circle. 
  • An arc is usually named by three points, two of which are the endpoints, and the third point lies between them. ABC is an arc and is denoted byCircles Class 5 Notes Maths  as shown in the picture below.

Circles Class 5 Notes Maths

  • Arcs are basically of two types,
    (i) Minor Arc
    (ii) Major Arc 
  • The Minor Arc is shorter and the Major Arc is longer.
  • ABC is a minor arc of the circle. LMN is a major arc of the circle.

Circles Class 5 Notes Maths 6. Circumference

  • Circumference is the perimeter or boundary of a circle.
  • Circumference = 2 x π x r
    = 2 x r x π
    = diameter x π ( because diameter = 2 x radius )

Interior and Exterior of Circle

In this, we will see through a diagram about which points are interior and exterior point

Circles Class 5 Notes Maths

It is clear that

  • R lies in the interior of the circle.
    Thus, OR < OA.
  • C lies in the exterior of the circle.
    Thus, OC > OA.
  • B lies on the boundary of the circle.
    Thus, OA = OB.

Did You Know

Concentric circles are circles with the same centre but different radii.

Circles Class 5 Notes Maths

Question for Chapter Notes: Circles
Try yourself:
Which term refers to a line segment with endpoints on the circle that passes through the centre?
View Solution

Drawing a Circle with Compass

  • To draw a circle with a compass, fix a pointed pencil in the compass.
  •  Place a ruler on the table, fix the metal tip of the compass at 0 of the ruler and open the compass to fix the end of the pencil at the given measure (say = 3 cm.)Circles Class 5 Notes Maths
  •  Next, take a point ‘O’ on a plane paper and rest the metal tip of the compass at point ‘O’.
  •  Hold the head of the compass firmly and move the pencil around to form a circle of radius 3 cm.

Circles Class 5 Notes Maths

Examples

Example 1: Find the diameter of a circle whose radius is 1.4 cm.

Note: The region enclosed between two concentric circles is called a ring.

Sol: Radius = 1.4 cm
Diameter of a circle = 2 × radius = 2 × 1.4 cm = 2.8 cm.

Example 2: Find the radius of a circle whose diameter is 6.8 cm.

Sol: Diameter = 6.8 cm
Radius = Diameter ÷ 2 = 6.8 cm ÷ 2 = 3.4 cm.

Example 3: Find the circumference of a circle whose radius is (a) 7 cm (b) 3.5 cm. [Take π = 22/7]

Sol: (a) Radius = 7 cm
Circumference of the circle = 2 × π × radius = 2 × 22/7 × 7 = 44 cm.
(b) Radius = 3.5 cm = 7/2 cm.
Circumference of the circle = 2 × π × radius
= 2 × 22/7 x 7/2 cm = 44/2 = 22 cm.

Example 4: The length of the diameter of a circle is 2.8 cm. Find the circumference of the circle.

Sol: Diameter = 2.8 cm = 28/10 .
Circumference of the circle = π × diameter = 22/7 x 28/10
= 22 x 4/10 = 88/10
= 8.8 cm.

Question for Chapter Notes: Circles
Try yourself:What is the circumference of a circle with a radius of 5.6 cm?
View Solution

The document Circles Class 5 Notes Maths is a part of the Class 5 Course Mathematics for Class 5.
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FAQs on Circles Class 5 Notes Maths

1. What are the important terms related to a circle?
Ans. Important terms related to a circle include radius, diameter, circumference, chord, tangent, secant, and center. The radius is the distance from the center to any point on the circle, while the diameter is twice the radius and passes through the center. The circumference is the total distance around the circle.
2. How can we identify the interior and exterior of a circle?
Ans. The interior of a circle refers to all the points that are inside the circle, while the exterior refers to all the points outside the circle. The boundary of the circle itself is defined by the circumference, which separates the interior from the exterior.
3. What steps should be followed to draw a circle with a compass?
Ans. To draw a circle with a compass, first place the pointed end of the compass at the center point where you want the circle to be. Then, adjust the other end of the compass to the desired radius length. Keeping the pointed end stationary, rotate the compass 360 degrees to draw the circle.
4. What is the difference between a chord and a tangent in a circle?
Ans. A chord is a line segment whose endpoints lie on the circumference of the circle, while a tangent is a line that touches the circle at exactly one point. The chord divides the circle into two arcs, whereas the tangent does not intersect the interior of the circle.
5. Can you give examples of real-life objects that resemble a circle?
Ans. Yes, many real-life objects resemble a circle. Examples include a round clock, a pizza, a bicycle wheel, a coin, and the face of a basketball. Each of these objects has a circular shape, showcasing the properties of a circle in everyday life.
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