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Geometry Pad is a dynamic geometry application for iPad.  With the Geometry Pad you can create fundamental geometric shapes, explore and change their properties and calculate metrics. The shapes are displayed on a scrollable and zoomable workbook with a rectangular coordinate system. The following tools are built into the application:  - Move and scale. Scroll the workbook by your finger. Pinch and zoom the content of your workbook. Move and modify shapes.  - Point. Plot a point on the workbook. Customize point name and color.  - Line. Create a line. Customize line style, color and start/end points. Calculate line length (distance between points).  - Midpoint for lines. Show/hide midpoint for lines and polygon sides. Snap to midpoints.  - Parallel, perpendicular and tangent lines. The lines can be created as easily as regular lines. Just create and move the line until it automatically snaps to parallel, perpendicular or tangent.  - Angle. Create an angle with up to 1 degree precision. Customize angle line style and color.  - Triangle. Create a triangle of one of the predefined types: regular, right triangle, isosceles, equilateral. Customize sides style and color. Calculate triangle perimeter and area. Calculate inner angles of the triangle and length of its sides.  - Triangle lines. Create altitude, bisector and median lines in a triangle. Calculate length of triangle lines. Customize lines style and color.  - Quadrilateral. Create a quadrilateral of one of the predefined types: regular, square, rectangle, parallelogram, rhombus. Customize sides style and color. Calculate quadrilateral perimeter and area. Calculate inner angles of the quadrilateral and length of its sides.  - Circle. Create a circle. Calculate circle perimeter and area. Easily create circles inscribed into a triangle by placing circle's center close enough to the incenter of a triangle.  - Circle radius and chord. Create radius and chord lines for a circle. Customize lines style and c

This slide show demonstrates some techniques that would be suitable for an experimental geometry project. The basic shapes of square and circle are explored using open source Geogebra and Dr Geo geometry software. The examples includes exercises in geometric construction, novel solutions and recursive (spiral) constructions. This is mathematics that can be done without algebra. There is some algebra on slide 18, to calculate the radius and area of a semicircle inscribed in a square.

Informal Geometry comes to us through MathMastery -- November's Featured Partner. This video-rich content provides students with the concepts and skills necessary for finding the perimeter, area, surface area and volume of common geometric figures; graphing equations on the coordinate system and deriving the equation for the third line from a pair of points; using the Pythagorean Theorem to solve problems involving right triangles; determining if triangles are similar and finding an unknown side in similar triangles; and determining unknown angles in figures by calculating the sum of the interior angles.