Irina Boyadzhiev  My GeoGebra Applets
Categories:
 ♦ Geometry
 ♦ Trigonometry
 ♦ Conic Sections
 ♦ Algebra, Precalculus and Calculus
 ♦ The Limaçon
 ♦ Optimization Problems
 ♦ Bézier Curves
 ♦ The Equiangular Spiral and Fibonacci Numbers
 ♦ Series
 ♦ Number Sense  Fractions
 ♦ Geometry for K9 Teachers
 ♦ Catacaustics
New
 Circumference of a Circle and Pi
 Trigonometric Functions with Variable Amplitude, Feb. 2015
 Graphs of Trigonometric Functions, Feb. 2015
 Coterminal and Reference Angles, Feb. 2015
 Radians, Number Line and the Unit Circle, Jan. 2015
 Visual Proof – a fraction between two given fractions
 Golden Triangles and Infinite Series , March 2014
 Line Symmetries and the Quadrilaterals Feb. 2014
 Midsegments and Congruent Triangles, Jan. 2014
Geometry
 Construction Vs Drawing Oct. 2009
 Midsegmens and Congruent Triangles, Jan. 2014
 The Area of the Median Triangle  Dynamic Proof, Jan. 2014

Dynamic Proof of Equal Areas, Dec. 2013

The Law of Cosines, Dec. 2013
 The Ninepoint Circle Oct. 2009
 Medians and Triangles with Equal Area Oct. 2009
 Intersecting Secants Theorem 2010
Some Geometry Problems
Trigonometry
 Radians, Number Line and the Unit Circle, Jan. 2015
 Trigonometric Functions with Variable Amplitude, Feb. 2015
 Graphs of Trigonometric Functions, Feb. 2015
 Coterminal and Reference Angles, Feb. 2015
Conic Sections
 Conic Sections  A Geometric Construction using the Eccentricity 2010, Modified Feb. 2014
 Geometric Construction of a Hyperbola and an Ellipse with Asymptotes and Directrixes 2010, Modified Feb. 2014
Algebra, Precalculus and Calculus
 Domain and Range of a Function, Jan 2013

Domainand Range of a Function by Flattening to the Axis, Jan 2013

Vertical
Line Test
, Sept. 2013
 Inverse Function , Sept.2013
 Horizontal Line Test , Sept. 2013
The Limaçon
 Limaçon as a Roulette  1 Nov. 2010
Optimization Problems
 Rectangle with maximum area if the perimeter is fixed Oct. 2009
 Rectangle with Maximum Area inscribed in a triangle Oct. 2009; Modified Jan. 2014

An Isosceles Triangle with Fixed
Perimeter
, Sept.2013

Area of an Isosceles Triangle with Fixed Two Equal Sides,
Sept. 2013
Bézier Curves
 Bézier Curves  Equations , Apr. 2012 Modified Jan. 2014
 Bezier Curves  Recursive Construction , Apr. 2012; Modified Jan. 2014
 PolyBézier curves, Dec. 2014
The Equiangular Spiral and Fibonacci Numbers
 GeoGebra construction of an Equiangular Spiral  1 2010
 GeoGebra construction of the Pedal and Copedal curve of an Equiangular Spiral 2010
 Measuring Equiangular Spirals in Nature 2010,
update
March 2012
 GeoGebra investigation of the Equiangular Spiral in Plants; Fibonacci Numbers , March 2012

Building of Fibonacci squares and Fibonacci Spiral,
March 2012

Fibonacci Spiral 
demonstration
, March 2012
 GeoGebra investigations of equiangular spirals in the flight of insects Nov. 2011
Series
 Golden Triangles and Infinite Series , March 2014

Infinite
Geometric Series  Sum of Areas of Triangles
,
May 2013
 The Sum of the First n Natural Numbers  Dynamic Geometric Proof , March 2013
 Arithmetic Series  Dynamic Geometric Proof , March 2013
 The Sum of the Cubes of the First N Natural Numbers , April 2013
 The Sum of Squares  Dynamic Geometric Proof , Feb. 2013
 The sum of the first N odd numbers , March 2013
Number Sense  Fractions
 Fractions, Feb. 2013
 Equivalent Fractions  One Common Misconception , Feb. 2013
Geometry for K9 Teachers
 Triangles with Equal Area
 Definition of a Circle, Jan. 2014
 Dynamic Proof of the Pythagorean Theorem

Properties
of Parallelograms
, Oct. 2013
 Theorems and Postulates for Congruent Triangles , March, 2012; Modified Jan. 2014
 The sum of the acute angles in a right triangle
 The Sum of the Interior Angles of a Triangle, Jan. 2014
 The sum of the interior angles in Any Triangle by Rotation and Translation
 The Sum of the Exterior Angles of Any Triangle
 Line Symmetries and the Quadrilaterals Feb. 2014
Some Simulations
 Rolling a rectangle; Perimeter 2011
 Rolling a Circle Circumference of a Circle, an Approximation of π, Radian Measure Oct. 2011
Arc Bound Squarable Shapes
Catacaustics
 Catacaustic of a Circle  Parallel Rays Oct. 2011
 Catacaustic of a Circle  Radial Rays Oct. 2011
 Catacaustic of an Ellipse  Parallel Rays Oct. 2011
 Catacaustic of an Ellipse  Radial Rays Oct. 2011
 Catacaustic of a Parabola  Parallel Rays Tschirnhausen Cubic Oct. 2011
 Catacaustic of a Parabola  Parallel Rays Oct. 2011
 Catacaustic of a Parabola  Radial Rays Oct. 2011
 Catacaustic of a Hyperbola  Radial Rays Oct. 2011

Catacaustic
of a Hyperbola  Parallel Rays
Oct. 2011