Geometry

Geometry Two-Minute Proofs

• Area of a parallelogram: http://www.geogebra.org/m/D8rjsGzF
• Area of a trapezoid: http://www.geogebra.org/m/CgbeDBpd
• Area of a circle
  • As a parallelogram: http://www.geogebra.org/m/fyqAUV22
  • As a triangle: http://www.geogebra.org/m/BqPZzXwu
• Volume of a sphere: http://www.geogebra.org/m/chZEfhwy
• Pythagorean Theorem
  • Many different versions: http://www.cut-the-knot.org/pythagoras/
  • Proof without words: http://www.geogebra.org/m/jFFERBdd#material/ATE2XV8p
  • Using similar triangles: http://www.geogebra.org/m/vGdDpaTu
• Writing the equation of a circle
  • Using the box method of multiplication: http://bit.ly/2vEmPQC
  • Animation: http://www.geogebra.org/m/e6NG57eT
  • As a translation of a circle centered at the origin: http://www.geogebra.org/m/ZGm2nN8N
• Triangle Inequality Theorem: http://www.geogebra.org/m/hq5R8kB7
• Sum of the interior angle measures of a triangle: http://www.geogebra.org/m/jEvQMDzj
• Sum of the exterior angle measures of a triangle: http://www.geogebra.org/m/KWb7RrTu