Angle Rules
Complementary & Supplementary Angles
NAME  RULE  DIAGRAM 
Complementary angles  Add to 90 degrees  
Supplementary angles  Add to 180 degrees 
(Hint to remember these: C in the alphabet and 90 when counting both come before S and 180.)
Vertically Opposite Angles
NAME  RULE  DIAGRAM 
Vertically opposite angles  Equal 
Angles of Parallel Lines
NAME  RULE  DIAGRAM 
Corresponding angles  (F shape)  
Cointerior angles  Add to 180 degrees (U shape)  
Alternate angles  Equal (Z shape) 
Angles of Triangles
NAME  RULE  DIAGRAM 
Angle sum of triangle  Add to 180 degrees  
Equilateral triangle  All angles equal 60 degrees  
Isosceles triangle  Base angles are equal  
Exterior angle of triangle  The exterior angle equals the sum of the two interior opposite angles. 
Question  Angle Sum of Triangle
To show that the angle sum of a triangle equals 180 degrees, draw a triangle, tear the angles and rearrange them into a straight line. Remember that the number of degrees in a straight line is 180 degrees.
Do a similar activity to show that the angles of a quadrilateral add to 360 degrees.
Angles of Quadrilaterals
NAME  RULE  DIAGRAM 
Angle sum of quadrilateral  Add to 360 degrees  
Opposite angles of parallelogram  Equal 
Angles of Circles
NAME  RULE  DIAGRAM 
Radius meets tangent  The radius meets the tangent at right angles.  
Angle at centre  The angle subtended at the centre of the circle is twice the angle at the circumference. (arrow shape) 

Angle at circumference  Angles subtended by the same chord are equal. (butterfly shape) 

Opposite angles of cyclic quadrilateral  Equal  
Exterior angle of cyclic quadrilateral  The exterior angle of a cyclic quadrilateral is equal to the interior opposite angle. 