Geometrical

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A point is usually represented by a small dot and is name by a single capital letter of alphabet<see fig.1>.It has no magnitude i.e. has no length, breadth or thickness.

Fig.1

Fig.2 A B

A ray is a part of a line, which has one end point, and extends indefinitely on the other side<see fig.1>

A

A plane is a flat surface that extends indefinitely in all directions. The surface of the wall is an example of a plane.<see fig.1>.

Fig.1

An angle is formed by two rays starting from the same initial point. The initial point O is called the vertex. Rays OA and OB are called the arms of the angle.

O

A

B

TRIANGLETriangle is a three side closed figure formed by three line segment intersect in pairs A,B and C are known as vertices of the Triangle.

A

B C

TRIANGLEHave Three side AB, BC and CA.

A

B C

TRIANGLE HAVE THREE ANGLE <A, <B, < C.

A

CB

INTERIOR

EXTERIOR

NO

D

ALTITUDE

A quadrilateral is a four sided figure. ’ Quadri ’ means four, and ‘ lateral ‘ means sides. If A,B,C and D are four points in a plane such that no three of them are collinear and the line segments AB,BC,CD and DA do not intersect except at their end-points, then the figure formed by these four line segments is called the quadrilateral ABCD.

A D

B C

ADJACENT SIDES

BC & AD are opposite sides.

A circles a set of points on a plane which are at the same distance from a fixed point called centre (O).

Circumference

Diameter

The circumference of a circle is the distance around the outside of a circle

The diameter of the circle is the distance from one side to the other passing through the centre of the circle

Radius

Chord

A chord is a line touching the circumference of the circle at two points

The radius is the line connecting the centre of the circle and the circumference

Sector

Arc

A sector is the part of a circle between two radii and an arc

An arc is the part of the circumference at the edge of a sector

Segment

Tangent

A segment is the part of a circle between a chord and an arc

A tangent is a straight line which touches a circle at one point only

Radius Diameter Sector Segment

Tangent Arc Circumference

Chord

Copy the two diagrams carefully into your book

Label your two diagrams using the words below