How this calculation works
Both an acute angle and its supplement have the same sine. A candidate is possible only if there is room left for the third angle.
Use sin(B) = b sin(A)/a and test both B and 180°−BA worked example
With A=30°, a=7 and b=10, both angles with sin(B)=5/7 leave a positive third angle.
Good to know
Near a tangency, classification depends on numerical precision.
Reference: OpenStax Algebra and Trigonometry, Trigonometric Applications (opens in a new tab) ↗
Read the result
Determine whether two sides and a non-included angle give zero, one, or two triangles.
The primary result is labeled “Possible triangles”. Keep the input definitions in view when comparing this result with another method.
Try a related calculation
Near a tangency, classification depends on numerical precision.
For a related exercise, try the circle calculator.
A few questions, answered
How can I check the default inputs by hand?
With A=30°, a=7 and b=10, both angles with sin(B)=5/7 leave a positive third angle.
Which rule does this calculator apply?
Use sin(B) = b sin(A)/a and test both B and 180°−B