Download Congruence - Maths FYI

GCSE Mathematics (1-9) 2015
How To Do it
G5Theory
Geometry -Congruence - 5
use the basic congruence criteria for triangles (SSS, SAS, ASA, RHS)
1
Congruence
Two triangles are congruent if one can be
transformed into the other just by translations,
rotations or reflections.
So congruent triangles have the same size and
shape. The corresponding side lengths and angles
are equal, but the triangle may be moved, turned or
flipped.
2
SSS
Two triangles can be proved to be congruent in different ways. These are remembered
using 3 letters like SSS.
SSS is side-side-side. They are congruent if they have 3 pairs of equal sides.
3
SAS
Side-angle-side
They are congruent if they have a pair of sides equal, and the angle between them is
equal (the included angle ).
4
ASA
Angle side angle
A pair of sides equal, and the angles at each end of the side (so, two angles and the
included side)
5
RHS
Right angle - hypotenuse - side
Triangles are congruent if they have a right angle, the hypotenuses are equal (side
opposite the right angle), and another side is equal.
GCSE Mathematics (1-9) 2015
How To Do it
Not SSA Two sides and a not included angle
does not mean congruence, since we can
draw it in two ways:
G5Theory