Page 143 - Math Skill - 4

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4. Write the names of the angles.

R X N

(a) (b) (c)
Z M
Q P Y L
F
5. From the given figure, write the name of points which are:
(a) in the exterior of ∠DEF L P
(b) in the interior of ∠DEF R
Q
Circle E M D

We have already learnt about the circle. It is a shape made up of a curved line.
Circle is a curved shape with all its points lying at the same distance from a fixed
point (centre). A

Parts of the Circle

Centre M P

The point at which we had kept the metal arm of the compass fixed O
can be marked as O. The point O is the centre of the circle.

Radius R

If we join any point on the circle to the centre of the circle we get a line segment.

This is called a radius of the circle.

Here, OP, OM and OR are the radii of the circle O. (Radii is the plural of radius).

If we measure OP, OM and OR, then we will find that they all have the same length. These
are the lengths of the radii of circle O.

B Chord
Chord D If any two points on a circle are joined, we get a line segment. This is

M called a chord of the circle. Here, AB and CD are the chords of the circle.
A
Chord A circle has many chords. Chords can have different lengths.

C P

Diameter

A chord of a circle which passes through its centre is called a diameter. M O N
Here, MN and PQ are diameters of circle O.

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