Sectors, Arcs, Segments in Circles, using Radians

An interactive applet investigating lengths of arcs, areas and perimeters of sectors, and areas of segments and isosceles triangles using formulae based on Radians (Radian measure)

Author and programmer: Ron Barrow

UK Years 12-13, KS5 AS and A2 Level Core Mathematics, Trigonometry


Instructions below    See also:   This applet using Degrees(°)   Print

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How to Use this Applet

On the circle you can move points A and B around by clicking them and dragging them with your mouse to new positions. This also can change the size of the circle.
Clicking the circular buttons at the bottom has these effects:
Clicking "sector" highlights a sector of the circle.
Clicking "arc" highlights an arc on the circle's circumference
Clicking "triangle" highlights the isosceles triangle formed by A, B and the centre.

Clicking "segment" highlights either the major segment or the minor segment formed by the chord AB.
Clicking "show working" displays some calculations at the right of the screen. You should study these carefully. Enjoy yourself while you learn these important techniques.