Law of Sines Calculator

Solve a triangle with the law of sines from an angle, its opposite side, and a second angle. Enter the two angles and the side.

Side b
—
Opposite angle B.

Usage Tip

The law of sines is ideal for ASA and AAS triangles; for two sides and an included angle, use the law of cosines.

THE MATH
a ÷ sin A = b ÷ sin B = c ÷ sin C
Every side over the sine of its opposite angle is equal
The law of sines relates each side of a triangle to the sine of its opposite angle.
It solves triangles when you know an angle and its opposite side, plus one more angle or side.
Enter angle A, the side opposite it, and angle B.
The third angle is 180 minus the other two.
Angles must sum to less than 180 degrees.
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