What is the law of cosines?

Answer by  LuptonsavedbyJesusyahoocom (32)

You have a triangle with sides A, B, and C. You know the lengths of A and B, but not C. You know the angle between A and B is theta. So the length of C is A^2 + B^2 - 2*A*B*cos(theta).

Answer by  janedoe (701)

It's a formula for finding the side of a triangle when the opposite angle and the other sides are known. The formula is c^2 = a^2 + b^2 - 2abcosC.

Answer by  VB (361)

a^2 = b^2+c^2-2*b*c*cos(A) relates all three sides of ANY triangle and one angle. Remember side a and angle A must be opposites.

Answer by  AJ (112)

The law of cosines is: c^2 = a^2+b^2-(2*a*b*cos(Θ)) where a, b, and c, are the lengths of each side of a triangle, and Θ (theta) is the angle opposite the side c. It's useful when you have the lengths of two sides, and the angle between them, but you need to know the length of the third side.

Answer by  Clement (1453)

The law of cosines is a generalization of the Pythagoras' theorem for arbitrary triangles. Formally the law of cosines says: c^2 = a^2 + b^2 - 2*a*b*cos(g), where a,b and c are sides of a triangle and g is an angle opposing c.