an equation for area or circumference of a decagon?

Answer 1

I assume you are talking about regular decagon? If that is the case then I think I can answer it. A regular decagon is a regular polygon with 10 sides.
The formula is: Area=1/2(ap), where a = apothem, p = perimeter of the polygon.

You can go to the following website to read the meaning of apothem and other geometric terms you will need to understand the formula.
From: http://www.sparknotes.com/math/geometry2/measurements/section6.rhtml

teddy boy

Answer 2

This Site Might Help You.

RE:
an equation for area or circumference of a decagon?

Answer 3

A general formula for the area of any regular polygon is NV^2sin(pi/N)cos(pi/N) where N is the number of sides and V is the distance from the center of the polygon to the vertex.

Answer 4

http://mathforum.org/dr.math/faq/formulas/index.html

just click on Regular Polygon, this will show you how to find the area, as for the circumference, use

R = a csc(alpha/2)/2

Answer 5

OMG I JUST DID THIS IN MATHS to figure out the area: pi r squared and circumferance: 2 pi r r = radius

Answer 6

P = 10s
A = 10(s/2)(s/2)tan18° ≈ 0.8122992s^2