Waste less time on Facebook — follow Brilliant.
×

What's the perimeter of a sphere?

Say the perimeter of a unit cube is 12, because that's the sum of all its edges, hence it's the cube's perimeter.

What would it be for a sphere of any proportion?

Note by Tim Ye
4 years, 3 months ago

No vote yet
5 votes

Comments

Sort by:

Top Newest

We don't call the sum of the edge lengths of a polyhedron its "perimeter." A perimeter is the boundary of a two-dimensional figure.

Because a sphere has no edges, it has no such sum as you have defined with the cube. Your question is analogous to asking for the number of vertices of a circle. There is none. Hero P. · 4 years, 3 months ago

Log in to reply

I interpret it as the sum of edges of a solid by your example of a cube. But a sphere has no edges, so the 'perimeter' is 0. If you are talking about adding all those tiny circumferences of the sphere up, you end up integrating them into the surface area of the sphere, \(4\pi r^2\). Yong See Foo · 4 years, 3 months ago

Log in to reply

@Yong See Foo Correct. Tim Ye · 4 years, 3 months ago

Log in to reply

@Yong See Foo Well you're just too smart for a 14 year old. I think that is kinda the answer. Sanjay Ambadi · 4 years, 3 months ago

Log in to reply

Tim Y. has already defined a "perimeter" of a 3D solid to be the sum of its edges. It is on our part, and not his, to understand what is implied. Wee Xian Bin · 4 years, 3 months ago

Log in to reply

There is no perimeter in 3 dimensional.Please clarify your question Edsel Salariosa · 4 years, 3 months ago

Log in to reply

We define perimeter for 2-dimensional figures only. Vikram Waradpande · 4 years, 3 months ago

Log in to reply

i don't think it has a perimeter......as it is a 3D figure........ Riya Gupta · 4 years, 3 months ago

Log in to reply

@Riya Gupta bebzz.... see figure chaiye 3D ho yah 2D ....hum haar time perimeter find kaar sakte hai because vo humesha hi line segments se banni hoti hai .... and the figures with curves ,,hum unka circumfrence find kaar sakte hai ...."CIRCUMFRENCE" ......................remember hum circle ka circumfrence find karte thei......... same way sphere ka bhi circumfrence nikkal sakta hai. Reshav Gupta · 4 years, 3 months ago

Log in to reply

@Reshav Gupta srry cant read hindi lol XD Bob Yang · 4 years, 3 months ago

Log in to reply

@Reshav Gupta AND I would like to say one more thing.....next time dont...put ur silly...comments...in hindi..... Riya Gupta · 4 years, 3 months ago

Log in to reply

@Riya Gupta It's same as that of a CIRCLE .......... 2pi R = circumfrence Reshav Gupta · 4 years, 3 months ago

Log in to reply

@Reshav Gupta You cannot find the circumference of a sphere as such but you can find the circumference of the circles in it. Aditya Parson · 4 years, 3 months ago

Log in to reply

@Aditya Parson decreasing...radii circles....will be there... Riya Gupta · 4 years, 3 months ago

Log in to reply

@Reshav Gupta U are wrong,think of a sphere like a figure made of many circles of various sizes,the biggest being at the center,and decreasing gradually.what u said wouldn't make sense now would it? Beakal Tiliksew · 4 years, 3 months ago

Log in to reply

@Reshav Gupta ohhh i guess you aren't familiar...with sphere and its properties....it cant be 2pi R Riya Gupta · 4 years, 3 months ago

Log in to reply

@Riya Gupta I DON'T THINK SO ....... Reshav Gupta · 4 years, 3 months ago

Log in to reply

@Reshav Gupta BUT I THINK SO.....AND BEFORE WRITING ANYTHING.....THINK OVER IT.......it will involve a typical integration with limits..... i think BK MAESTER T...is right..... Riya Gupta · 4 years, 3 months ago

Log in to reply

@Reshav Gupta ohk.....toh aap meko sphere ka " CIRCUMFERENCE " find karke do.....plzzzzz........woh bhi curve hai na........? :/

[ i said
fine! if is it so...then find "CIRCUMFERENCE" of...sphere since its a curve tooo....]
as u quoted "and the figures with curves ,,hum unka circumfrence find kaar sakte hai ...."CIRCUMFRENCE" same way sphere ka bhi circumfrence nikkal sakta hai. "

aur jab ho jae toh btana....me yahi milungi....except for the condition ki tum use kisise pucho ya fir koi search engine khol kar uspe se copy...paste karo.....huh....

[ i said when u'll finish that....post it here i'll be here only.....and terms and conditions for u.....DONT ASK IT FROM SOMEONE AND DONT CHEAT IT FROM SOME SEARCH ENGINE.....OK...] Riya Gupta · 4 years, 3 months ago

Log in to reply

probably undefined since there are no edges on a sphere Tan Li Xuan · 4 years, 3 months ago

Log in to reply

Well, going by your definition, lets say the sphere has infinite sides, then Perimeter = (infinity) x (whatever is the value of each side) p = ∞ But wait, the length of each side is zero as they are just points. ∴ p = ∞ x 0 = 1 (if you can consider that as true) Hence your answer is 1. Sanjay Ambadi · 4 years, 3 months ago

Log in to reply

Perimeter doesn't apply to 3 dimensional figures. It is the boundary of a 2 dimensional figure.Since, 3 dimensional figures don't have any boundary , so, neither a sphere nor a cube has a perimeter. Prakkash Manohar · 4 years, 3 months ago

Log in to reply

Guyss.... first of all , cube is also a 3D figure and In the figures like that of a circle or a sphere ,we don't take perimeter ,there it's circumfrence . And in sphere we can have the circumfrence .. agree? Reshav Gupta · 4 years, 3 months ago

Log in to reply

×

Problem Loading...

Note Loading...

Set Loading...