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Center and Radius

Part of the Circles section of Coddy's Geometry journey. Lesson 1 of 59.

A goat is tied to a post with a 5 m rope. It walks as far as the rope lets it, in every direction. It leaves a ring of hoofprints. Every print is exactly 5 m from the post.

$A post O with a rope 5 metres long$

Challenge

The dots are hoofprints. Each one is exactly 5 m from the post O. Drag P to a new spot that is also exactly 5 m from O. Put it in the gap between the prints on the right and at the top.

Then press Check.

Try it yourself

$Drag the figure and watch$

Drag the figure and watch

All lessons in Circles

1Parts of a Circle

Center and RadiusChords and Diameters Recap: Parts of a Circle

4Arcs and Sectors

Arc Length Area of a Sector Find the Central Angle The Missing Central Angle Recap: Arcs and Sectors

7Angles in a Semicircle

Thales' Theorem The Right Angle Inside Is That Enough?Semicircle With Letters Recap: Semicircles

10Tangents

What a Tangent Is Tangent and Radius Tangent Lengths Two Tangents From a Point Tangents With Letters Recap: Tangents

2Circumference

The Hexagon Inside Around the Circle Radius From Circumference Recap: Circumference

5Radii Make Isosceles

Two Radii, One Triangle Base Angles From the Center The Angle at the Center Isosceles With Letters Recap: Radii and Triangles

8Angles on the Same Arc

Same Arc, Same Angle Using the Same Arc Spot the Bow Tie Same Arc With Letters Recap: Same Arc

11Circle Chases

Tangent Meets Chord Two Roads to One Angle Enough to Find It?Cyclic Meets Isosceles Recap: Circle Chases