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Law of Cosines

★★★☆☆High School

📖Definition

The Law of Cosines relates one side of a triangle to the other two sides and their included angle. It generalizes the Pythagorean theorem.

c² = a² + b² - 2abcos C

Law of Cosines

cos C = (a² + b² - c²)/(2ab)

Law of Cosines (for finding angles)

예제 1

Find c when a = 5, b = 7, and C = 60°.

Discovered by: Ancient Greek mathematicians

Appeared in geometric form in Euclid's Elements; the modern formula developed with trigonometry.

Triangulation

Positioning algorithms

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