RIC-1069 Maths terms and tables

Triangles
Other triangle facts
Sum of the angles in a triangle
The sum of the angles in a triangle is
always 180°.
e.g.
108º
50º 22º
Exterior angles
Each exterior angle is equal to the sum
of the two opposite interior angles.
e.g.
b
a
a + b
Pythagorean theorem
In a right-angled triangle the square on
the hypotenuse is equal to the sum of
the squares on the other two sides
[see p. 43].
e.g.
Hypotenuse is the
longest side.
Similar triangles
Two triangles are similar if they have the same shape, but not necessarily
the same size. Being the same shape means that corresponding angles are
congruent and the corresponding sides are in the same ratio [see below].
Conditions for similarity
Diagram
Side-side-side (SSS)
If the lengths of the three corresponding sides (SSS) of
two triangles are in the same ratio, then the triangles are
similar.
2
3
1
2
3
1
Angle-angle (AA)
If two angles of a triangle are congruent to two angles of
another triangle, then the triangles are similar.
Side-angle-side (SAS)
If one angle of a triangle is congruent to one angle
of another triangle and the lengths of the sides (SAS)
that determine these angles are in the same ratio, then
the triangles are similar. [Note that the angles that are
congruent must be between the sides that are in the
same ratio, hence the A is placed in the centre of the SAS
as a reminder.]
1
1
2
2
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