20 sides 1/2*(202-60) = 170 diagonals
A regular octogon (8 sides) has 20 diagonals. An irregular octogon also has 20 diagonals, but only if all its points point outwards.
Kinds of polygons with their meanings are: Convex (all diagonals are internal), concave (at least one diagonal is outside the shape), equilateral (equal sides), equiangular (equal angles), regular (equal angles and sides), irregular, (no equal angles and sides), triangle (3 sides), quadrilateral (4 sides), pentagon (5 sides), hexagon (6 sides), heptagon (7 sides), octagon (8 sides), enneagon or nonagon (9 sides), decagon (10 sides), hendecagon (11 sides), dodecagon (12 sides), tridecagon or triskaidecagon (13 sides), tetradecagon or tetrakaidecago (14 sides), pendedecagon (15 sides), hexdecagon (16 sides), hepdecagon (17 sides), ocdecagon (18 sides), enneadecagon (19 sides) and icosagon (20 sides).
There is no limit to the number of sides that a particular shape can have. The Icosahedron has 20 sides. It would tend to the circle as the number tends to infinity: even a 360-sided polygon (1 degree internal angles) would look a bit like like a pixellated circle.
Well, honey, a shape with 20 sides is called an icosagon. It's like a polygon on steroids, with all those sides flaunting their angles like they're on a runway. So next time you need to impress someone with your geometry knowledge, just drop the word "icosagon" and watch them swoon.
Sides: 8 Diagonals : 20
20 sides and 170 diagonals
20 sides
It has 20 diagonals
20 sides 1/2*(202-60) = 170 diagonals
All polygons have 3 or more sides having exterior angles that add up to 360 degrees and the first 10 can be classed as follows in order of their geometrical names, number of sides, sum of interior angles and number of diagonals:- 1 Triangle: 3 sides, 180 degrees and no diagonals 2 Quadrilateral: 4 sides, 360 degrees and 2 diagonals 3 Pentagon: 5 sides, 540 degrees and 5 diagonals 4 Hexagon: 6 sides, 720 degrees and 9 diagonals 5 Heptagon or Septagon: 7 sides, 900 degrees and 14 diagonals 6 Octagon: 8 sides, 1080 degrees and 20 diagonals 7 Nonagon: 9 sides, 1260 degrees and 27 diagonals 8 Decagon: 10 sides, 1440 degrees and 35 diagonals 9 Undecagon: 11 sides, 1620 degrees and 44 diagonals 10 Dodecagon: 12 sides, 1800 degrees and 54 diagonals Note that all polygons can be regular, irregular, congruent or similar
The formula for determining the number of diagonals in a shape is n(n-3)/2 where n=vertices, (corners or intersections of geometric shapes). For an eight sided shape we replace n with 8. 8(8-3)/2 8(5)/2 (8x5)/2 40/2=20 An octagon contains 20 diagonals. For a further example we can determine the diagonals in a shape with 5 sides: 5(5-3)/2 5(2)/2 (5x2)/2 10/2=5 A Pentagon contains 5 diagonals.
a square i hope your not older than 20
A regular octogon (8 sides) has 20 diagonals. An irregular octogon also has 20 diagonals, but only if all its points point outwards.
170
All 8 sides must be equal in length Interior angles add up to 1080 degrees Exterior angles add up to 360 degrees Each interior angle measures 135 degrees Each exterior measures 45 degrees It has 6 triangles It has 20 diagonals
A polygon with n sides had n*(n-3)/2 diagonals. So a 20 sided polygon would have 20*17/3 = 170