Area of a rectangle. Definition and formula
A web page and interactive applet showing the ways to calculate the area of a rectangle. The user can drag the vertices of the rectangle and the other points change automatically to ensure it remains a rectangle. A grid inside the shape allows students to estimate the area visually, then check against ...
Author(s): John Page

Area of a square. Definition and formula
An interactive applet and associated web page that demonstrate the area of a square. The applet shows a square with all vertices draggable. As you drag any one, the area id continuously calculated and shown on the applet. The square is filled with a unit grid to allow class estimation of area. The displayed ...
Author(s): John Page

Area of a trapezoid. Definition and formula
A web page and interactive applet showing the ways to calculate the area of a trapezoid. The user can drag the vertices of the trapezoid and the other points change automatically to ensure it remains a trapezoid. A grid inside the shape allows students to estimate the area visually, then check against ...
Author(s): John Page

Area of a triangle (conventional method)
An interactive applet and associated web page that explain the area of a triangle. The applet shows a triangle that can be reshaped by dragging any vertex. As it changes, the area is continually recalculated using the 'half base times height' method. The triangle has a fixed square grid in its interior ...
Author(s): John Page

Definition of a Square
An interactive applet and associated web page that demonstrate the properties and behavior of a square. The applets shows a square with all vertices draggable. As you drag any one, the others move to ensure the figure remains a square. It can be seen that the sides remain parallel and congruent, and ...
Author(s): John Page

Intersecting Secant Theorem
An interactive applet and associated web page that demonstrate the 'Intersecting Secants Theorem'. The applet shows a circle and two secant lines intersecting at a point outside the circle. The secant points and the external point are draggable. As you drag them the secant lines are redrawn and a realtime ...
Author(s): John Page

Median of a triangle
A web page and interactive applet illustrating the medians of a triangle. The applet shows a triangle where the user can drag the vertices to reshape it. As the triangle is being reshaped, the user can see the three median lines tracking the changes, and observe that that all three always intersect ...
Author(s): John Page

Rectangle
A web page and interactive applet showing the definition and properties of a rectangle. The applet shows a rectangle where the user can drag any vertex. The other points then move in such a way that the figure remains a rectangle at all times. A control to hide the details allows a classroom discussion ...
Author(s): John Page

Rhombus
A web page and interactive applet showing the definition and properties of a rhombus. The applet shows a rhombus where the user can drag any vertex. The other points then move in such a way that the figure remains a rhombus at all times. A control to hide the details allows a classroom discussion where ...
Author(s): John Page

Rhombus area formula
A web page and interactive applet showing the ways to calculate the area of a rhombus. The user can drag the vertices of the rhombus and the other points change automatically to ensure it remains a rhombus. A grid inside the shape allows students to estimate the area visually, then check against the ...
Author(s): John Page

Right triangle
An interactive applet and associated web page that demonstrate the three types of triangle: acute, obtuse and right. The applet shows a triangle that is initially right (one angle 90 degrees) which the user can reshape by dragging any vertex. There is a message changes in real time while the triangle ...
Author(s): John Page

Scalene triangle
An interactive applet and associated web page that demonstrate the properties of scalene triangles. The applet presents a scalene triangle where any vertex can be dragged to reshape it. As it is dragged, the length of the sides and interior angles are continuously changed. If a change is made that causes ...
Author(s): John Page

Secant
An interactive applet and associated web page that demonstrate a secant to a circle. (not trig). The applet shows a circle and a secant line. The points where the secant cross the circle are both draggable. As you drag each, the secant line moves. If you carefully make the two points coincide, it shows ...
Author(s): John Page

Segment of a Circle
An interactive applet and associated web page that demonstrate a segment of a circle - a part of a circle cut off by a chord. The applet shows a circle and a segment of that circle, the ends of which can be dragged to resize the segment. You can create the situation where the chord is a diameter and ...
Author(s): John Page

Similar Triangles
An interactive applet and associated web page that demonstrate the concept of similar triangles. Applets show that triangles are similar if the are the same shape and possibly rotated, or reflected. In each case the user can drag one triangle and see how another triangle changes to remain similar to ...
Author(s): John Page

Tangent to a circle
An interactive applet and associated web page that demonstrate a tangent to a circle. (not trig). The applet shows a circle and a tangent line. The center point and the tangent contact point are both draggable. As you drag each, the figure changes to ensure that the line is always tangential to the ...
Author(s): John Page

Tetragon
A web page and interactive applet illustrating the properties of a tetragon (4 sided polygon). The applet shows a tetragon where the user can drag any vertex to reshape the polygon. User can see that the interior and exterior angles are constant in a regular tetragon, but vary in an irregular version. ...
Author(s): John Page

Thales theorem
A web page and interactive applet illustrating Thales Theorem (the diameter of a circle always subtends a right angle to any point on the circumference). The applet shows a circle where the user can rotate the diameter and a move a point on the circumference. The applet continuously shows the resulting ...
Author(s): John Page

The Golden Rectangle
An interactive applet and associated web page that illustrate the properties the 'Golden Rectangle' whose sides are in the 'golden Ratio' of 1 : 1.618 : 1. The applet shows a golden rectangle whose vertices a re draggable. When dragged the rectangle changes to remain in the that shape. The web page ...
Author(s): John Page

Transversal
An interactive applet and associated web page that demonstrate the transversal, a line that crosses two other (usually parallel) lines. The applet shows two lines that are initially parallel, and a transversal line. All eight angles thus formed are shown. As you drag the transversal end points, you ...
Author(s): John Page