Carpentry & Building Construction © 2004

Polygons

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Carpenters build structures of different shapes and sizes. Many are in the shape of polygons. A polygon is a closed, flat figure with straight sides. Polygons have at least three sides. Triangles are three-sided polygons.

Squares, pentagons, and hexagons are examples of regular polygons. A regular polygon has equal sides and equal angles.

A rectangle is a four-sided polygon in which the opposite sides are equal and the four angles are each 90 degrees.

Practice Exercise

1. An exterior door

An exterior door has four sides. The top and bottom are of equal length, and the left and right are of equal length. Each angle is 90 degrees. Therefore the door is a rectangle.
2. An eight-sided window

An eight-sided window has eight equal sides. Therefore it is an octagon.
3. A 12'' × 12'' floor tile

The tile has four equal sides. It is a square.
4. A six-sided deck

A deck with six equal sides is a hexagon

1.		A carpenter is preparing to install a window with five equal sides. This shape is a(n)
			A)	heptagon.
			B)	hexagon.
			C)	pentagon.
			D)	octagon.
2.		The end of a 4'' × 4'' × 8' post is a
			A)	rectangle.
			B)	square.
			C)	triangle.
			D)	hexagon.
3.		An outdoor gazebo to be built has eight sides, in the shape of a(n)
			A)	pentagon.
			B)	hexagon.
			C)	heptagon.
			D)	octagon.
4.		A roof truss uses this basic shape to support the roof materials.
			A)	triangle
			B)	square
			C)	pentagon
			D)	rectangle
5.		Since a 4' × 8' sheet of plywood is a rectangle, each angle equals
			A)	45 degrees.
			B)	60 degrees.
			C)	75 degrees.
			D)	90 degrees.