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number of diagonals in an n-sided polygon is n(n-1)/2 - n
If the polygon has 12 sides, number of diagonals is 12(12-1)/2 -12
= (12)(11)/2 -12
= 132/2 - 12
= 66-12 = 54
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∙ 12y ago
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How many diagonals does a 2d decagon have?
54 Diagonals. * * * * * A polygon with n sides has 1/2*n*(n-3) diagonals. So a decagon would have 1/2*10*7 = 35 diagonals. How the Community answer got 54 is anybody's guess!
Are all quadrilaterals with congruent diagonals parallelpgram?
No. An isosceles trapezium (isosceles triangle with its apex removed) would have congruent diagonals but it is not a parallelogram.
On a parallelogram do the diagonals cross at right angles?
They might, but they do not have to. A very long and narrow parallelogram would have diagonals that cross at a very sharp angle.no they donot
How many diagonals are in an octagon?
An Octagon has 20 diagonals in total. There is actually a really simple formula to figuring out the diagonals in any polygon: (n-3) x (n/2). If we put 8 in there than it would be (8-3) x (8/2) - 5x4=20, so the answer is 20 diagonals.
Does a rhombus have equal diagonals?
No. If they were equal the rhombus would become a square.
Where is the centre of gravity what objects situated Rhombus?
That would be at the point where the diagonals of the figure intersect.
What kind of parellogram is it If the diagonals of a parallelogram are congruent and are perpendicular bisectors of each other?
If the diagonals are congruent and are perpendicular bisectors of each other then the parallelogram is a square. If the diagonals are not congruent but are perpendicular bisectors of each other then the figure would be a rhombus.
How many diagonals in a 2-dimensional equilateral figure?
The number of diagonals in an equilateral figure can be calculated from the number of sides. If the number of sides is "S", then the number of diagonals would be S(S-3)/2 This becomes clear if you consider that there will be the same number of vertices as there are sides. From each vertex you can draw a diagonal to all vertices except the one you started from and the two adjacent ones (lines between the adjacent vertices and the starting point are sides of the figure, not diagonals). This gives you S·(S-3) but that would double count the diagonals since each diagonal can start at either vertex.
Is there 2 diagonals in a triangle?
There are no diagonals in any triangle. This is because any line connecting two of the vertices would actually be one of the sides. A diagonal has to run through the middle of the figure...well, not the exact center but you know what I mean :)
Does a parallelogram have perpendicular diagonals?
No, not necessarily. It would have to also be a square or a kite in order to have perpendicular diagonals.
What is Justification Math?
Justification is a written reason for why you made a statement. For example if you say a figure is a Square then you would say something like the diagonals are both congruent and perpendicular to each other.
What regular polygon has 9 diagonals?
A regular octadecagon (an eighteen sided polygon) would have nine diagonals.
Which shape has diagonals which are equal?
Any rectangle will have diagonals that are equal. Don't forget that since squares are also a special type of rectangle that they would also have congruent diagonals as well.
Are the diagonals of an isosceles triangle congruent?
Yes, the diagonals of an isosceles triangle are congruent. This is because an isosceles triangle has two sides that are equal in length, which creates two congruent triangles when the diagonals are drawn.
What would you call a kite with congruent diagonals?
A square.
What is the relationship between diagonals on a rhombus?
Not in general. The diagonals of a rectangle are equal length. A rhombus that is also a rectangle would be a square.
How many diagonals does a 2d decagon have?
54 Diagonals. * * * * * A polygon with n sides has 1/2*n*(n-3) diagonals. So a decagon would have 1/2*10*7 = 35 diagonals. How the Community answer got 54 is anybody's guess!
