sin(A+B)

Use the Next button to advance through the proof of sin(A+B)=sin(A)cos(B)+sin(B)cos(A).
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This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

Questions:

1. How could we find a formula for cos(A+B) using this construction?

2. What would be different for sin(A-B)?

Dixie Christensen, 16 November 2013, Created with GeoGebra