Complementary & Supplementary Angles
|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
|Vertically opposite angles||Equal|
Angles of Parallel Lines
|Corresponding angles||(F shape)|
|Co-interior angles||Add to 180 degrees (U shape)|
|Alternate angles||Equal (Z shape)|
Angles of Triangles
|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
|Angle sum of quadrilateral||Add to 360 degrees|
|Opposite angles of parallelogram||Equal|
Angles of Circles
|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.
|Angle at circumference||Angles subtended by the same chord are equal.
|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.|