Objects > Circles

Circles

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Circles

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Circles are fundamental objects in Euclidean geometry. In classical geometric constructions, you use a compass to construct circles.

A circle is a path object.

You can change the object properties, label properties, and display attributes of circles.

Construct a Circle

Sketchpad provides several different ways to construct a circle.

Use the Compass tool to construct a circle using a center point and another point which defines the radius.

Use the Construct | Circle by Center+Point command to construct a circle using a center point and another point which defines the radius.

Use the Construct | Circle by Center+Radius command to construct a circle using a center point and either a segment or a distance measurement to define the radius.

Use a Circle

Construct a point on a circle using the Point tool or the Construct | Point on Object command. Then animate the point around the circle or use the point as the driver for a locus.

Attach an independent point to the circle by using the Edit | Merge command.

Use Construct | Interior to construct the interior of a circle.

Use Construct | Intersection to construct a circle’s intersection with a straight object, another circle, an arc, a point locus, or a function plot.

Use Graph | Define Unit Circle to define a coordinate system that uses the selected circle as its unit circle.

Measure a Circle

Use the Measure menu to find:

the Circumference of a circle

the Radius of a circle

the Area of a circle

the Equation of a circle