Port Said International Schools – National Section
Better education for future generations
Handout No. : 1(geo.)
Date:
Name :____________________________________________ Grade:7
Types of angle:
Name of the angle
1) Zero angle
The figure
Description
When the two sides of
the angle are coincided
to each other ( = Zeroº )
2) Acute angle
It’s measure is greater
than zero but less than
90º
3) Right angle
It’s measure equals to
90º exactly ( = 90º )
4) Obtuse angle
It’s measure is greater
than 90º but less than
180º
5) Straight angle
It’s measure equals to
180º exactly ( = 180º )
6) Reflex angle
It’s measure is greater
than 180º but less than
360º
Math Department
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Relations between angles:
(1) Adjacent angles:
*Two angles are said to be adjacent if :
1. They have a common vertex and a common side.
2. The other two sides are on opposite sides of this common side.
*  ABD and  DBC are two adjacent angles , for :
1. They have a common vertex B and a common side BD
2. The other two sides BA and BC are on opposite sides of BD
 BAC and  EDC are not adjacent
 BAC and  BAD are not adjacent
because they have not a common
vertex.
because the sides AC and AD are
not on the opposite sides of AB
(2)Complementary angles:
*Two angles are said to be complementary if the
sum of their measure is 90o.
35o +55o = 90o
(3)Supplementary angles:
*Two angles are said to be complementary if the
sum of their measure is 180o.
55o +125o = 180o
Math Department
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*Remarks :
1. Two adjacent angles formed by a straight line and a ray with a starting point on this
straight line are supplementary
2.If two adjacent angles are supplementary then their outer sides are on the same straight
line.
(4) Vertically opposite angles:
*If two straight lines intersect , then the measure of each
two vertically opposite angles are equal
 AMD and  CMB
 CMA and  BMD
Vertically opposite angle
Vertically opposite angle
(5) Accumulative angles at a point:
*The sum of the measures of the accumulative angles
at a point is 360o
 AMD +  DMC +  CMB +  BMA = 360o
(6) Angle bisector:
*An angle bisector is a ray the divides an angle
into two halves.
AM divides  BAD into two angles having the same
measure and AM is called the bisector  BAD
Math Department
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