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Plane trigonometry involves solving the mathematics of triangles. The law of sines and cosines are fundamental to this.

Law of sines[edit]

Area of a triangle[edit]

Law of cosines[edit]

This law uses the Pythagorean theorem, but this includes non-right angles.

Heron's area formula[edit]

s is the semi-perimeter


[1] [2]

  1. Trigonometry (7th ed.), Addison Wesley, 2001, 0-321-05759-7 |access-date= requires |url= (help)
  2. "Trigonometry". Britannica 28: 619. (1993). University of Chicago. 0-85229-571-5. Retrieved on Jan 2, 2013.