Page 327 - Math Smart - 7

Internal angles in regular polygons

If a shape Is regular, all of Its angles are of the same size.

~lo°
108° 108

O
0
90°^ 120° 120

Equilateral triangle Square Regular pentagon Regular hexagon Regular octagon

Constructing regular polygons

40 mm A .''//

Mathematics Connect
J

Many engineers are engaged in structural engineering: from aerospace engineers who design
satellite structures, to civil engineers who design bridges and flyovers, to mechanical engineers
who design vehicle chassis and the placement of components inside computers and cell phones.
Geometric shapes, such as hexagons and triangles, play a very important role in strengthening
structures that are used to support the entire construction.
Structural engineers make use of connector plates to help strengthen connecting points on bridges
and buildings. A connector plate is most commonly shaped as a triangle, square or even a parabola.

A motorcycle frame design consists of two triangles
to support the wheels and seats. Mechanical
engineers design cranes that use triangles and
squares in their frames. Even satellites use these m
familiar and basic regular geometries.
The image on the right shows a geodesic dome
called the Montreal Biosphere. The structure of
geodesic domes is similar to the structure of soccer
balls and appears to be made up of a group of
pentagons and hexagons. But, if we break each of
those shapes down, we can see that they are made
up of triangles.