Angles Revision Guide
Sr. No.
1
2
3
4
5
Property
Sum of angles on a straight line is 180°
Sum of angles at a point is 360°
Sum of a complementary angles is 90°
Sum of supplementary angles is 180°
Vertically opposite angles are equal in size
How to Reference
∠s on a str. Line
∠s at a point
Comp. ∠s
Supp. ∠s
Vert. opp. ∠s
6
7
8
Corresponding angles are equal in size
Alternate angles are equal in size
The sum of co-interior angles is 180°
Corr. ∠s
Alt. ∠s
Co-int. ∠s
9
Sum of interior angles of any polygon is equal to 180
(n-2) for an n-sided shape
Sum of exterior angles of any polygon is 360°
Sum of angles in a triangle is 180°
Sum of angles in a quadrilateral is 360°
Sum of 2 interior angles of a triangle is equal to
exterior opposite angle
10
11
12
13
14
15
16
17
18
19
20
Alternate segment theorem
Angle at the centre theorem
Angles in the same segment theorem
Angles in a semicircle
Chord of a circle
Cyclic quadrilateral
Tangent of a circle
Σ of int. ∠s of poly.
Σ of ext. ∠s of poly.
Σ of ∠s in △
Σ of ∠s in quad.
Σ of int. ∠s equal to ext. opp. ∠
Alt. seg.
∠ at centre twice ∠ at circum.
∠s in same seg.
∠s in semi-circ.
⊥ bisect. of chord
cyc. quad.
tang. to circ.