Page 73 - Maths Class 06

2. Identify the longest side in the follow ing triangles using the method of obser vation:
(a) P (b) A (c) T S

Q R P
C B
3. Draw PT = 6 cm. Mark a point S on PT lying between P and T. Verify that PS = PT - ST.
4. A B C D E F G H I J K

0 1 2 3 4 5 6 7 8 9 10 11
Using the number line (drawn above). Verify:
(a) E is midpoint of AI (b) AF + FK = AK
(c) AJ - BJ = AB (d) G is the midpoint of FH

Angles
As read in previous chapter, an angle is made up of two rays starting 80 90 100 110
120
from common endpoint. An angle is measured using a geometrical 50 60 70 110 100 80 70 60 130
120
40 130 50 140
instrument called protractor. It is semi-circular in shape and two scales 30 140 40 150
are marked from 0 to 180°. It resembles the English alphabet letter D. 20 160 150 30 20 160
10 170 10 170
To measure a given angle ABC, place the centre of the protractor on 0 180 0 180
the vertex B of arm BC of ÐABC. Protractor
100 90 80
110 70
120 60
130 50
A 140 A 40
150 30
160 20
170 10
O
B C 180 B C 0
Adjust the protractor so that BC is along the straight line of protractor. Read the degree mark shown by
BA on the protractor’s curved edge. ÐABC = 60 °

Types of Angles

S. No. Types of an gles along with fig ures Figures

1. Acute an gle:

An angle whose measure is less than 90° is an
acute angle.

2. Right an gle:

An angle whose measure is exactly 90° is a right
angle.

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