U:\S_data\mydata\word\tutorial\maths gen.doc 11-Dec-13

Summary of Geometric Rules 1 Angle subtended at centre = 2 x angle subtended at circumference 2 Angles in same segment are equal 3 Angle subtended by diameter = 90 4 Cyclic quadrilateral : opposite angles are supplementary 5 Exterior angle of a cyclic quadrilateral = interior opposite angle 6 Tangent to a circle is perpendicular to the radius drawn through the point of contact 7 Parallel lines cut by a third line :

7.1 corresponding angles are equal 7.2 alternate angles are equal 7.3 interior angles are supplementary

8 Vertically opposite angles are equal 9 Sum of interior angles for an n-sided polygon = ( 2) 180n − × 10 Pythagoras theorem : 2 2 2a b c+ = 11 isosceles triangle : 2 angles equal 12 Congruent triangle :

12.1 SAS 12.2 AAS 12.3 SSS 12.4 RHS

13 Exterior angle of triangle = sum of interior opposite angles 14 Alternate segment theorem : angle between a tangent to circle and a chord through the point of

contact = an angle in the alternate segment