I assume you mean, that an angle and two sides are known.
A formula that can be used for irregular triangles is the cosine rule.
'b' and 'c' must be sides that are beside the angle 'A' (angle opposite 'a').
A formula that can be used for irregular triangles is the cosine rule.
'b' and 'c' must be sides that are beside the angle 'A' (angle opposite 'a').