Arc Peripheral Angle

Abstract:: An interactive applet and associated web page that demonstrate the concept of the peripheral angle (inscribed angle) of an arc. This is the angle subtended at the circle circumference of an arc. The applet shows an arc with draggable end points and the angle it subtends at the circumference. It is seen that this angle is constant for a constant arc length. It shows also what happens when the vertex is inside the arc that subtends it The web page has links to other arc properties and a formula for the subtended angle for a given arc length. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

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Inscribed angle of a circle

Abstract:: An interactive applet and associated web page that demonstrate the inscribed angle of a circle - the angle subtended at the periphery by two points on the circle. The applet presents a circle with three points on it that can be dragged. The inscribed angle is shown and demonstrates that it is constant as the vertex is dragged. Links to other related topics such as Thales Theorem. Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.

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Abstract:: A web page and interactive applet demonstrating the concept of the incircle of a triangle - the largest circle the will fit inside a triangle. The applet shows a triangle where the user can drag the vertices around. The incircle is continuously adjusted as the user drags the vertices. By experimentation the user can observe that the three sides of the triangle are always tangents to the incircle. The page text explains the definition of the incircle and how to draw it. It describes how the incenter is the center of the incircle of the triangle with a link to that page http://www.mathopenref.com/triangleincircle.html Applet can be enlarged to full screen size for use with a classroom projector. This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.