Wolfram Demonstrations Project

This Demonstration provides a visual proof of the formula

The area of the large rectangle is

. The area of colored quadrilateral is

. It equals the sum of the pink triangle with area

and the brown triangle with area

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

RELATED RESOURCES

Mathematica » The #1 tool for creating Demonstrations and anything technical.	Wolfram\|Alpha » Explore anything with the first computational knowledge engine.	MathWorld » The web's most extensive mathematics resource.	Course Assistant Apps » An app for every course— right in the palm of your hand.
Wolfram Blog » Read our views on math, science, and technology.	Computable Document Format » The format that makes Demonstrations (and any information) easy to share and interact with.	STEM Initiative » Programs & resources for educators, schools & students.	Computerbasedmath.org » Join the initiative for modernizing math education.
Step-by-step Solutions » Walk through homework problems one step at a time, with hints to help along the way.	Wolfram Problem Generator » Unlimited random practice problems and answers with built-in Step-by-step solutions. Practice online or make a printable study sheet.	Wolfram Language » Knowledge-based programming for everyone.

The Sum of the Sines of a Sum and Difference of Two Angles