Maths CAT - geometry

Equilateral Triangle

Equilateral triangle

All edges are the same

length and all angles

are the same size.

This is shown by the

identical marks on each

edge and each angle.

isosceles triangle

a triangle with two equal sides

scalene triangle

A triangle with no equal sides

reflex angle

Between 180 and 360 degrees

rectangle

Opposite sides are equal in length.

Adjacent sides are perpendicular.

All angles are the same and equal 90°.

rhombus

All sides are equal in length.

Opposite angles are equal in size.

square

All sides are equal in length.

Adjacent sides are perpendicular.

All angles are the same and equal 90°.

Trapezium

One pair of opposite sides is parallel.

Kite

Two pairs of adjacent (next to each other)

sides are equal in length.

One pair of opposite angles (the ones that

are between the sides of unequal length) are

equal.

Irregular Quadrilateral

This shape does not have any special

properties.

Vertically opposite / adjacent angles

vertically opposite angles are always equal. Adjacent angles are two angles that share a common arm and vertex.

Complementary angles

Complementary angles are adjacent angles that add up to 90°.

In this diagram, x + y = 90°

Supplementary angles

Supplementary angles are adjacent angles that add up to 180°.

In this diagram, x + y = 180°.

Parallel lines

lines in the same plane that do not intersect

Transversal

The term 'transverse' means 'crossways'. A line that intersects with a pair of parallel lines is called a

transversal.

Corresponding Angles

Corresponding angles are

positioned on the same side of

the transversal and are either both

above or both below the parallel

lines. Think of them as F-shaped.

Co-interior Angles

Co-interior angles are positioned

'inside' the parallel lines, on the

same side of the transversal. Think

of them as C-shaped.

Co-interior angles are also called

allied angles.

Alternate Angles

Alternate angles are positioned

'inside' the parallel lines on

alternate sides of the transversal.

think of them as Z-shaped.

Vertically opposite angles

Vertically opposite angles are

created when two lines intersect.

The angles opposite each other

are equal in size. Think of them as

X-shaped.

perpendicular lines

two lines that intersect at a right angle. This is often shown by a right-angle symbol in the corner where the two lines meet. You can see perpendicular lines everywhere you go, from the corners of buildings to branches in the trees. They don't have to just be intersecting on a piece of paper either. Perpendicular lines can be side-to-side or vertical too.