Miss Norledge's Storeroom
  • Home
  • Resources by Topic
    • Number and Proportion
    • Algebra
    • Shape
  • Blog
    • Summer Blog Challenge
    • Staffrm 29 Days of Writing (2016)
    • Maths with Zoombinis
  • My resources
    • Downloads >
      • Mix Match
      • Rally Coach
      • Pass the Problem
    • Request a password
  • Links
    • Teaching blogs and resources
    • Web tools and apps
    • Exams and assessment
  • Privacy Policy
  • Home
  • Resources by Topic
    • Number and Proportion
    • Algebra
    • Shape
  • Blog
    • Summer Blog Challenge
    • Staffrm 29 Days of Writing (2016)
    • Maths with Zoombinis
  • My resources
    • Downloads >
      • Mix Match
      • Rally Coach
      • Pass the Problem
    • Request a password
  • Links
    • Teaching blogs and resources
    • Web tools and apps
    • Exams and assessment
  • Privacy Policy

             

  

Circular thinking

13/2/2016

 
Picture
Post 13/29 in the Staffrm #29daysofwriting challenge: Naming the parts of a circle
It's another short(ish) post today because I'm trying to make the most of my first weekend of half term and also because I've done something weird to one of my fingers and typing/clicking is really painful today (fortunately, this also puts paid to any idea that I'll be marking books later).

​Following my post yesterday about integers, I got 
the following Twitter comment:
Ooh Etymology and maths! and of course "tangent" means "touching" #NumbersCount
This got me wondering about the other parts of a circle; in Romanes eunt domus (11/29) I discussed the origins of "radius", and now I'd been reminded about the Latin connection to tangent(from the verb tangere - to touch). And I've worked out the following:
  • Radius: as mentioned a couple of days ago, the word radius was used to refer to spokes of wheels on a chariot, which would go from the centre to the circumference of the wheel.
  • Centre: directly from centrum (centre), but originally from the Greek kentron (sharp point, barb), which ties nicely into construction of a circle using a pair of compasses, when you place the point where you want the centre of the circle to be.
  • Sector: from the verb secare (to cut); imagine cutting a slice from a (circular) cake, and that gives you a sector. We get a load of other English words from secare as well - 
  • Segment: from segmentum (a piece cut off, a strip of cloth); segmentum has the verbsecare as its original root. Interestingly, the word "segment" initially had a geometric meaning, and only started being used more generally later on.
  • Tangent: as above, from the verb tangere (to touch); a tangent just touches a circle at one place on the circumference.
  • Chord: from chorda (a string, usually of a musical instrument), and also linking to the musical meaning of chord.
  • Circumference: from circum (around) and ferre (to carry), combining into the verbcircumferre (to lead or carry around). Lots of other words in English beginning withcircum come directly from similar Latin verbs, such as circumspect, from circumspicere(literally "to look around", but also "to take notice").
  • Arc: from arcus (a bow or arch).

Strangely, although all of the other "circle words" have a traceable Latin origin, the word "diameter" doesn't - its root is purely Ancient Greek.
  • Diameter: from dia (across) and metron (measure); the diameter measures (the longest distance across the circle.

​(Image credit: By Tomruen - Own work, CC BY-SA 4.0, commons.wikimedia.org/w/index....)

Sheila Eastwood
16/2/2016 22:30:09

Yet another word for part of a circle that comes from secare is secant. It is now defunct at GCSE, but remembered by some old timers like me. A secant is a line that starts outside a circle, cuts across the circle, and continues out the other side - like a chord extended.
If you investigate the etymology of the names of the ratios in trigonometry, you will find that tangent theta is the tangent to the unit circle, and secant theta (reciprocal of cosine) is a secant to the unit circle


Comments are closed.

    Categories

    All
    #29daysofwriting
    A Level
    Algebra
    Algebra Tiles
    Area
    Assessment
    Bar Model
    Bar Modelling
    Books
    Celebration Of Maths 2015
    Challenge
    Circles
    CPD
    Cuisenaire Rods
    Data
    Decimals
    Displays
    Enrichment
    Equations
    Events
    Feedback
    Formulae
    Four Operations
    Fractions
    Functional Maths
    Gcse 2015
    GCSE Past Papers
    GCSE Revision
    Graphs
    Group Work
    HCF And LCM
    History Of Maths
    Intervention
    Investigation
    Lesson
    Lesson Ideas
    Literacy
    Lotw
    Loving Maths
    Manipulatives
    Marking
    Mastery
    #mathsconf
    #mathsconf2015
    #mathsconf4
    Maths In Pictures
    Multiplication
    Musings
    Negative Numbers
    News
    Numeracy Across Curriculum
    Parenthood
    Percentages
    Pick Of Twitter
    Pie Charts
    Primes
    Probability
    Problem Solving
    Proportion Problems
    Puzzles
    Pythagoras
    Quadratics
    Quadratic Sequences
    Ratio Tables
    Real Life Graphs
    Reflection
    Resources
    Revision
    Rounding
    Schemes Of Work
    Simultaneous Equations
    Square Numbers
    Stationery
    #summerblogchallenge
    #teacher5adaysketch
    Teaching And Learning
    Technology
    Top Ten
    Trignometry
    Trigonometry
    Vectors
    Venn Diagrams
    Websites
    Weebly Tutorials
    Zoombinis


    Archives

    August 2020
    September 2018
    August 2018
    October 2017
    July 2016
    June 2016
    May 2016
    February 2016
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015

    RSS Feed

Powered by Create your own unique website with customizable templates.