Works Cited

Larson, Ron and Robert P. Hostetler. Precalculus 6th ed. Boston: Houghton Mifflin Company, 2004. Print.

http://staff.jccc.net/swilson/trig/anglesumidentities.htm
Wilson, Steven. Angle Sum and Difference Identities. Johnson County Community College. Web. 30 March 2011.

http://library.thinkquest.org/20991/alg2/trigi.html
"Trigonometric Identities." Math for Morons Like Us. Oracle. Web. 30 March 2011.

http://mathworld.wolfram.com/Half-AngleFormulas.html
Weinstein, Eric. "Half Angle Formulas." WolframMathWorld. Wolfram Research. Web. 30 March 2011.

http://www.algebralab.org/lessons/lesson.aspx?file=Trigonometry_TrigSumDifference.xml
"Sum and Difference Formulas." Algebra Lab. Mainland High School. Web. 30 March 2011.