# TRIANGLES HAVE STRONG SHAPES by Dr.Khin Maung Win (Maths)

MATHEMATICS 9

TRIANGLES HAVE STRONG SHAPES

We say that triangles have strong shapes.We define a strong shape in the following way.

Imagine some shapes constructed by joining pieces of wood together with nails or screws as shown here.

picture of shapes,

picture of Mg Yit holding the shape A strong shape is one that cannot changed without breaking the wood.One can alter the shape of quadrilateral or pentagon or hexagon without breaking the wood.But one cannot alter the shape of the triangle breaking the wood.That is why we say that triangles have strong shapes.

In building bridges ,towers and other things we use triangles,because triangles make them strong.

picture of bridge and tower

Because triangles have strong shapes , if we know one side of a triangle and the angles at each end, we know all the sides.We use this principle to find the distance of objects which cannot be reached.For example, distance of the ship at sea from the shore can be found by using this principle.

picture of ship at sea