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Category: Geometry

The-surface-area-of-a-cylinder-is-A-2pir-2-2pirh-As-h-0-the-shape-becomes-a-2D-circle-so-should-lim-h-0-A-pir-2-Or-is-it-that-as-h-0-it-creates-a-circle-of-3-dimensions-with-infinte

Question Number 5542 by FilupSmith last updated on 19/May/16 $$\mathrm{The}\:\mathrm{surface}\:\mathrm{area}\:\mathrm{of}\:\mathrm{a}\:\mathrm{cylinder}\:\mathrm{is}: \\ $$$${A}=\mathrm{2}\pi{r}^{\mathrm{2}} +\mathrm{2}\pi{rh} \\ $$$$ \\ $$$$\mathrm{As}\:{h}\rightarrow\mathrm{0},\:\mathrm{the}\:\mathrm{shape}\:\mathrm{becomes}\:\mathrm{a}\:\mathrm{2D}\:\mathrm{circle}, \\ $$$$\mathrm{so}\:\mathrm{should}\:\:\:\:\:\underset{{h}\rightarrow\mathrm{0}} {\mathrm{lim}}\:{A}\:=\:\pi{r}^{\mathrm{2}} \:\:\:??? \\ $$$$\mathrm{Or}\:\mathrm{is}\:\mathrm{it}\:\mathrm{that}\:\mathrm{as}\:{h}\rightarrow\mathrm{0},\:\mathrm{it}\:\mathrm{creates}\:\mathrm{a}\:\mathrm{circle} \\ $$$$\mathrm{of}\:\mathrm{3}\:\mathrm{dimensions}\:\mathrm{with}\:\mathrm{infintesimally}\:\mathrm{small}…

What-plane-geometrical-figures-could-be-produced-by-joining-vertices-of-a-cube-for-example-square-What-largest-area-2-dimensional-can-be-obtained-by-joining-vertices-of-a-cube-when-its-side-is

Question Number 5543 by Rasheed Soomro last updated on 19/May/16 $$\bullet\mathrm{What}\:\boldsymbol{\mathrm{plane}}\:\boldsymbol{\mathrm{geometrical}}\:\boldsymbol{\mathrm{figures}} \\ $$$$\mathrm{could}\:\mathrm{be}\:\mathrm{produced}\:\mathrm{by}\:\mathrm{joining} \\ $$$$\boldsymbol{\mathrm{vertices}}\:\boldsymbol{\mathrm{of}}\:\boldsymbol{\mathrm{a}}\:\boldsymbol{\mathrm{cube}}? \\ $$$$\left(\mathrm{for}\:\mathrm{example}\::\:\mathrm{square}\right) \\ $$$$\bullet\mathrm{What}\:\mathrm{largest}\:\mathrm{area}\left(\mathrm{2}\:\mathrm{dimensional}\right)\:\mathrm{can}\:\mathrm{be}\:\mathrm{obtained} \\ $$$$\mathrm{by}\:\mathrm{joining}\:\mathrm{vertices}\:\mathrm{of}\:\mathrm{a}\:\mathrm{cube}\:\mathrm{when}\:\mathrm{its}\:\mathrm{side}\:\mathrm{is}\:\mathrm{x}? \\ $$ Terms of…

How-many-planes-can-pass-through-vertices-of-a-cube-a-when-each-plane-contains-at-least-three-vertices-b-when-each-plane-contains-exactly-four-vertices-c-Could-we-say-that-a-plane-can-pass-at-mo

Question Number 5539 by Rasheed Soomro last updated on 19/May/16 $$\mathrm{How}\:\mathrm{many}\:\boldsymbol{\mathrm{planes}}\:\mathrm{can}\:\mathrm{pass}\:\mathrm{through} \\ $$$$\boldsymbol{\mathrm{vertices}}\:\mathrm{of}\:\mathrm{a}\:\boldsymbol{\mathrm{cube}}, \\ $$$$\left.{a}\right)\:\mathrm{when}\:\mathrm{each}\:\mathrm{plane}\:\mathrm{contains}\:\boldsymbol{\mathrm{at}}\:\boldsymbol{\mathrm{least}} \\ $$$$\boldsymbol{\mathrm{three}}\:\boldsymbol{\mathrm{vertices}}. \\ $$$$\left.{b}\right)\:\mathrm{when}\:\mathrm{each}\:\mathrm{plane}\:\mathrm{contains}\:\boldsymbol{\mathrm{exactly}} \\ $$$$\boldsymbol{\mathrm{four}}\:\boldsymbol{\mathrm{vertices}}. \\ $$$$\left.{c}\right)\:\mathrm{Could}\:\mathrm{we}\:\mathrm{say}\:\mathrm{that}\:\mathrm{a}\:\mathrm{plane}\:\mathrm{can}\:\mathrm{pass} \\ $$$$\boldsymbol{\mathrm{at}}\:\boldsymbol{\mathrm{most}}\:\boldsymbol{\mathrm{four}}\:\boldsymbol{\mathrm{vertices}}?…

Measure-of-the-side-of-a-cube-is-double-of-the-the-side-of-the-cube-inside-it-What-is-empty-space-in-larger-cube-

Question Number 5533 by Rasheed Soomro last updated on 18/May/16 $$\mathrm{Measure}\:\mathrm{of}\:\mathrm{the}\:\mathrm{side}\:\mathrm{of}\:\mathrm{a}\:\mathrm{cube}\:\mathrm{is}\:\mathrm{double} \\ $$$$\mathrm{of}\:\mathrm{the}\:\mathrm{the}\:\mathrm{side}\:\mathrm{of}\:\mathrm{the}\:\mathrm{cube}\:\mathrm{inside}\:\mathrm{it}. \\ $$$$\mathrm{What}\:\mathrm{is}\:\mathrm{empty}\:\mathrm{space}\:\mathrm{in}\:\mathrm{larger}\:\mathrm{cube}? \\ $$ Commented by FilupSmith last updated on 18/May/16 $$\mathrm{Empty}\:\mathrm{space}\:\mathrm{is}\:\mathrm{equal}\:\mathrm{to}\:\mathrm{the}\:\mathrm{larger}…

Question-5529

Question Number 5529 by Rasheed Soomro last updated on 18/May/16 Commented by Rasheed Soomro last updated on 18/May/16 $$\bigtriangleup\mathrm{ABC}\:\mathrm{is}\:\mathrm{an}\:\mathrm{equilaterl}\:\mathrm{triangle}. \\ $$$$\mathrm{D},\mathrm{E},\mathrm{F}\:\mathrm{are}\:\mathrm{mid}-\mathrm{points}\:\mathrm{of}\:\mathrm{the}\:\mathrm{sides}. \\ $$$$\mathrm{The}\:\mathrm{centres}\:\mathrm{of}\:\mathrm{arcs}\:\mathrm{are}\:\mathrm{vertices}\:\mathrm{of} \\ $$$$\bigtriangleup\mathrm{ABC}.…

Question-5517

Question Number 5517 by Rasheed Soomro last updated on 17/May/16 Commented by Rasheed Soomro last updated on 17/May/16 $$ \\ $$$$\bullet\mathrm{ABC}\:\mathrm{is}\:\mathrm{a}\:\mathrm{triangle},\:\mathrm{D},\mathrm{E}\:\mathrm{and}\:\mathrm{F}\:\mathrm{are} \\ $$$$\mathrm{midpoints}\:\mathrm{of}\:\mathrm{the}\:\mathrm{sides}\:\mathrm{of}\:\mathrm{it}. \\ $$$$\bullet\mathrm{Centres}\:\mathrm{of}\:\mathrm{arcs}\:\mathrm{are}\:\mathrm{A},\mathrm{B}\:\mathrm{and}\:\mathrm{C}.…

If-you-have-a-regular-n-sided-polygon-is-there-a-method-to-calculate-the-area-from-one-corner-to-another-That-is-if-we-start-at-a-corner-corner-1-and-draw-a-line-to-corner-x-what-is-the-area-

Question Number 5515 by FilupSmith last updated on 17/May/16 $$\mathrm{If}\:\mathrm{you}\:\mathrm{have}\:\mathrm{a}\:\mathrm{regular}\:{n}−\mathrm{sided}\:\mathrm{polygon}, \\ $$$$\mathrm{is}\:\mathrm{there}\:\mathrm{a}\:\mathrm{method}\:\mathrm{to}\:\mathrm{calculate}\:\mathrm{the}\:\mathrm{area} \\ $$$$\mathrm{from}\:\mathrm{one}\:\mathrm{corner}\:\mathrm{to}\:\mathrm{another}? \\ $$$$ \\ $$$$\mathrm{That}\:\mathrm{is},\:\mathrm{if}\:\mathrm{we}\:\mathrm{start}\:\mathrm{at}\:\mathrm{a}\:\mathrm{corner}\:\left(\mathrm{corner}\:\mathrm{1}\right), \\ $$$$\mathrm{and}\:\mathrm{draw}\:\mathrm{a}\:\mathrm{line}\:\mathrm{to}\:\mathrm{corner}\:{x},\:\mathrm{what}\:\mathrm{is}\:\mathrm{the}\:\mathrm{area}? \\ $$$$\mathrm{See}\:\mathrm{image}\:\mathrm{in}\:\mathrm{comment}\:\mathrm{for}\:\mathrm{visual}\:\mathrm{representation}. \\ $$ Commented…