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Law of Sines Calculator

Use the Law of Sines to solve a triangle when you know two angles and one side (AAS or ASA).

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What the Law of Sines does

The Law of Sines relates the sides of any triangle to the sines of their opposite angles: a / sin(A) = b / sin(B) = c / sin(C). It lets you solve a triangle when you know two angles and one side (the AAS or ASA case), since the third angle follows from the fact that all three angles add up to 180 degrees.

How to use this calculator

Enter angle A, angle B, and the length of side a (the side opposite angle A). The calculator finds the missing angle C, then uses the Law of Sines ratio to solve for sides b and c.

This tool is for general educational and planning purposes. If the two given angles add up to 180 degrees or more, no valid triangle exists and the calculator will show zero.

Last reviewed August 2026