Download Remedial - MoreMaths

6
1. Revision
Description
Recall basics of
geometry
Reflect and Review
Teasers
Answers
The Front, Top and Side view 1) Write the name of the
of the solid shape
polygon shown below.
1) Hexagon
2) 41 cm
are as follows:
2) Find the diameter of a
circle of radius 20.5
cm.
Front view
Top view
Side view
2. Point, Line, Line Segment and Ray
Description
Reflect and Review

A point is a basic unit of
geometry.

A point represents position
only; it has zero size.
We represent a point by a dot and
name it with a capital letter, say A.
A
Teasers
List some examples
from your daily life
which reminds you of
a line, a line segment
and a ray.
1


A line is a collection of
points extending endlessly
in both the directions along
a straight path.
A line has no starting point
and no ending point.
A
B
Here, ⃡ is a straight line. The arrows
in two directions indicate that it goes
endlessly in both the directions.
A line can also be represented by k, l,
m, n, etc.

A part of a line is called a
line segment.

It has a starting point and
an ending point.
A
B
We call a line segment by means of its
starting point and its ending point as
line segment AB, and write it as ̅̅̅̅ or
̅̅̅̅.

A ray is a part of line which
has a starting point but
goes endlessly in the other
direction.
A
B
The direction in which the ray goes
endlessly and the starting point are
clearly indicated in the ray, and is
written as .
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3. Angle
Description
Reflect and Review
Teasers
Answers
Angle

When two rays meet The angle formed at O is written as
∠AOB or ∠BOA, where ∠ is the symbol
at a point, an angle
for an angle.
is formed.

The point where the
rays meet is called
the vertex and the
rays are called the
arms of the angle.
A
Angle

A degree is the unit
of measurement
used for measuring
angles and it is
symbolically
denoted as °.
O
B
Measuring Angles


We can use a
protractor to
measure angles.
A protractor has two
sets of
measurements
written on it. These
are called scales.

There is an inner
scale and an outer
scale, both having 0°
to 180° in different
directions.

There is a baseline
and the midpoint of
the baseline is called
centre.
Types of Angles
Measuring an angle ∠
C:
Step 1: Place the protractor over
∠ABC such that the centre point
coincides with the vertex B of the
angle and the baseline lies on the arm
BC of ∠ABC.
Draw an
angle using
scale and
pencil, and
find its
measure
using a
protractor.
Step 2: Note down the measure of the
angle against the arm BC counting
from 0°.
Thus, ∠ABC = 600.
1) Measure
1) 900
3
4

An angle measuring
less than 900 is
called an Acute
angle.

An angle measuring
exactly 900 is called
a Right angle.

An angle measuring
greater than 900 is
called an Obtuse
angle.

An angle measuring
exactly 1800 is called
a Straight angle.

An angle measuring
exactly 3600 is called
a Complete angle.
the angle
formed
between
the two
corners
edges of
you note
book.
2) Give
some
examples
of acute
angles
formed
while
writing
English
alphabets
.
2) A, K, M,
N, V, X,
Y, Z.
4. Perpendicular and Parallel Lines
Description


Reflect and Review
If the angle between two
intersecting lines is 900, then
the lines are said to be
Perpendicular to each other.
List some parallel
and
perpendicular
lines that you see
in your day to day
life.
P
The symbol ⊥ is used to
denote perpendicular lines.
Q
O
Teasers
R
In the figure, OP is perpendicular to
QR. It is written as: OP ⊥ QR.

If two lines never meet each
other and are at same
distance always, then they are
said to be Parallel lines.

The symbol || is used to
denote parallel lines.
C
A
D
B
In the figure, line AB is parallel to line
CD. It is written as: AB || CD.
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