Page 137 - Touchpad Mathematics_Ver1.0_C5

E:\Working\Orange_Education\TouchPad_Maths-5\Open file\Maths_5_Chapter-05
\ 19-Nov-2025 Bharat Arora Proof-9 Reader’s Sign _______________________ Date __________

 The two rays forming an angle are called the arms of the angle. The common
endpoint is called the vertex of the angle. Angles are measured in degrees,
denoted by °.

 Angles are of different types: 360° (complete angle), 90° (right angle), less than
90° (acute angle), between 90° and 180° (obtuse angle), 180° (straight angle)
and between 180° and 360° (reflex angle).
 A turn involves rotating an object around a fixed point. Each turn corresponds

to a specific angle measure. There are 360 degrees in a complete turn.
 On the basis of their side lengths, triangles are classified as equilateral, isosceles

and scalene.
 On the basis of their angles, triangles are classified as right-angled, obtuse-
angled and acute-angled.

 A circle is a closed curve such that all points on it are at an equal distance from
its centre. The radius of a circle is half of its diameter.
 A parallelogram has opposite sides that are equal and parallel, and its diagonals

bisect each other.
 A rectangle is a special parallelogram where all angles measure 90°, while a
square is a special rectangle where all sides are equal.
 A rhombus is a special parallelogram where all sides are equal, but its angles

are not necessarily 90°.
 A trapezium has one pair of parallel sides and a kite has two pairs of equal
adjacent sides.

 A polyhedron is a solid shape with flat faces, straight edges and vertices.

Learning LOGS

1. fill in the blanks.

a. When two rays form an angle, their common endpoint is called the ______ of the
angle.
b. Angles are measured in _________.

c. The measure of a _________ angle is 180°.

135
Geometry