Law of Sines
Pick what to find, then enter the known parts.
Result
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Enter numbers to see the result.
Third angle C
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Check a/sinA
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Formula: a/sin A = b/sin B = c/sin C. Side: b = a sin B / sin A. Angle: sin B = b sin A / a.
Solve triangles with the law of sines: find a missing side or a missing angle from known parts.
Pick what to find, then enter the known parts.
Enter numbers to see the result.
The law of sines says each side divided by the sine of its opposite angle is the same constant: a/sin A = b/sin B = c/sin C. That constant is the triangle's circumdiameter. Knowing any angle-side pair unlocks the rest of the triangle.
Given two sides and a non-included angle (SSA), the sine equation can yield two valid angles: an acute one and its supplement. The tool flags this ambiguity and shows the acute solution with the third angle computed.