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.)
NAME | RULE | DIAGRAM |
Vertically opposite angles | Equal |
NAME | RULE | DIAGRAM |
Corresponding angles | (F shape) | |
Co-interior angles | Add to 180 degrees (U shape) | |
Alternate angles | Equal (Z shape) |
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. |
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.
NAME | RULE | DIAGRAM |
Angle sum of quadrilateral | Add to 360 degrees | |
Opposite angles of parallelogram | Equal |
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. |