Chords and Diameters
Part of the Circles section of Coddy's Geometry journey. Lesson 2 of 62.
A chord is a segment that joins two points on a circle. A chord that passes through the center is a diameter. It cuts the circle into two equal halves, and it is the longest chord the circle has.
In the figure, CD is a chord: both ends are on the circle, but it misses the center. AB is a chord too, and because it goes through O it is a diameter. A diameter is made of two radii end to end, OA and OB, which is why it is twice as long as a radius.
Challenge
Three segments are drawn in circle O. Tap the one that is a diameter, then press Check.
Try it yourself
Find the right part on the figure
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Circles
1Parts of a Circle
Center and RadiusChords and DiametersAll Radii Are EqualDiameter Is Two RadiiRecap: Parts of a Circle4Arcs and Sectors
Arc LengthArea of a SectorFind the Central AngleThe Missing Central AngleRecap: Arcs and Sectors2Circumference
Around the CircleUsing the DiameterRadius From CircumferenceCircumference With LettersRecap: Circumference5Radii Make Isosceles
Two Radii, One TriangleBase Angles From the CenterThe Angle at the CenterIsosceles With LettersRecap: Radii and Triangles8Angles on the Same Arc
Same Arc, Same AngleUsing the Same ArcSpot the Bow TieSame Arc With LettersRecap: Same Arc3Area of a Circle
The Area FormulaArea From the DiameterRadius From the AreaCircumference to AreaRecap: Area of a Circle6Inscribed Angles
Meet the Inscribed AngleHalf the Central AngleTwice the Inscribed AngleThe Big ArcInscribed With LettersRecap: Inscribed Angles