Names for angles

< 90 = 90

90 < a < 180180 < a < 360

Compass points and bearings

North

East

South

West

000

090

180

270

Angles at a point

Angles on a line

Complementary angles

Opposite angles

Parallel lines: Corresponding angles

Parallel lines: Alternate angles

Parallel lines: Allied angles

Angles in a triangle

Named triangles...

Angles in a quadrilateral

Named quadrilaterals

Interior and exterior angles

Also called external and internal angles

PolygonsTriangle

Rectangle

Pentagon

Hexagon

Heptagon

Octagon

Nonagon

Decagon

Irregular

Regular

Exterior angles of a polygon

IrregularRegular

e = 360 n

e

Exterior angle must be factor of 360

Exterior angles add to 360

Interior angles of a polygon

Total internal angle

= (n – 2) ×180

Regular

(n – 2) ×180

n i =

i e

i = 180 - e

Circle angles