Av Richard Morgan • Uppdaterad 30 augusti 2022
Polygons—geometric figures formed by straight sides—come in many varieties, from simple triangles to complex star shapes. Common classifications include convex, concave, and regular polygons. A regular pentagon, for instance, is automatically convex because all its interior angles are equal and less than 180°.
Kommer från det grekiska ordet penta meaning “five,” a pentagon has five straight edges. In a regular pentagon, all sides and interior angles are equal, each measuring 108°. To compute the area of a regular pentagon, divide it into five congruent isosceles triangles. Beräkna arean av en triangel och multiplicera med fem. For example, if a single triangle covers 2.1 sq in, the entire pentagon occupies 10.5 sq in.
Med det grekiska prefixet hexa meaning “six,” a hexagon consists of six sides. A regular hexagon’s six angles each equal 120°. Its area can be found by partitioning it into six congruent equilateral triangles. Multiplying the area of one triangle by six gives the full area. Om en triangel är 2,1 kvm, mäter hexagonen 12,6 kvm.
Den grekiska termen okto betecknar "åtta", och en oktagon har åtta sidor. In a regular octagon, every side is equal and each interior angle measures 135°. Genom att dela formen i åtta kongruenta likbenta trianglar kan du bestämma dess area. Using the same example, an octagon with each triangle at 2.1 sq in totals 16.8 sq in.
Polygoner finns överallt. Det amerikanska försvarsdepartementets högkvarter, känt som "The Pentagon", är en stor, vanlig femkantig byggnad. Bees construct hexagonal cells in honeycombs to maximize storage and structural efficiency. Architects frequently employ octagonal designs for gazebos and other structures. Den allestädes närvarande stoppskylten i USA är en åttasidig oktagon som signalerar förare att stanna.
