www.reference.com/world-view/many-diagonals-octagon-a18d129ba60cdbf0

How Many Diagonals Does an Octagon Have? Credit: Gareth Williams/CC-BY-2.0. An octagon has 20 diagonals. A shape's diagonals are determined by counting its number of sides, subtracting three and multiplying that number by the original number of sides. This number is then divided by two to equal the number of diagonals.

www.answers.com/Q/How_many_diagonals_does_a_octagon_have

How many diagonals does an octagon have? A polygon with n vertices has n*(n-3)/2 diagonals. So an octagon has 8*5/2 = 20 diagonals. Of those 20 diagonals, 8 are the principal diagonals, the ones ...

magoosh.com/gre/2016/diagonals-of-a-regular-octagon-in-gre-geometry

Diagonals of a Regular Octagon. An octagon is any eight-sided polygon, and the sum of its angles is 1080°, as we saw above. In a regular octagon, each angle = 1080°/8 = 135° That angle is the supplement of a 45° angle. The regular octagon is the typical stop sign shape in many parts of the world. How many diagonals does an octagon have?

www.quora.com/How-many-diagonals-are-there-in-octagon

How many diagonals does a triangle and a regular hexagon have? Is it possible to prove that the diagonals of a parallelogram are not necessarily equal? What is the area of the largest octagon, which can be cut out from a square of perimeter 96?

mathcentral.uregina.ca/QQ/database/QQ.09.03/glenn1.html

First you need to know how many diagonals a regular octagon has and then how many have the longest length. Draw an octagon, select one vertex and construct each diagonal from this vertex.You will see there are 5 such diagonals. Thus for each of the 8 vertices you can draw 5 diagonals and hence you have constructed 5 8 = 40 diagonals. But you ...

quizlet.com/331361396/other-polygons-flash-cards

How many sides does an octagon have? 8. If all of the diagonals are drawn from a vertex of a pentagon, how many triangles are formed? 3. If all of the diagonals are drawn from a vertex of a hexagon, how many triangles are formed? 4.

www.mathsisfun.com/geometry/polygons-diagonals.html

An octagon has 20 diagonals: A polygon's diagonals are line segments from one corner to another (but not the edges). The number of diagonals of an n-sided polygon is: n(n − 3) / 2. Examples: a square (or any quadrilateral) has 4(4−3)/2 = 4×1/2 = 2 diagonals;

quizlet.com/111433443/assignment-23-other-polygons-flash-cards

How many sides does an octagon have? 8. ... A polygon is such that when all diagonals from one vertex are drawn, eleven triangles are formed. How many sides does the polygon have? ... Assignment - 23. Other Polygons (Vocabulary) 5 Terms. Chandra_Hinkle. Assignment - 21. Exterior and Remote Interior Angles of a Triangle 3 Terms.

www.wikihow.com/Find-How-Many-Diagonals-Are-in-a-Polygon

Draw some other polygons and count the number of diagonals. The polygon does not have to be symmetric for this method to work. In the case of a concave polygon, you may have to draw some of the diagonals outside the actual polygon. A hexagon has 9 diagonals. A octagon has 20 diagonals.

answers.yahoo.com/question/index?qid=20080705044510AApWftM

First you need to know how many diagonals a regular octagon has and then how many have the longest length. Draw an octagon, select one vertex and construct each diagonal from this vertex.You will see there are 5 such diagonals. Thus for each of the 8 vertices you can draw 5 diagonals and hence you have constructed 5 8 = 40 diagonals.