Detailed description
Two triangles side by side. Triangle ABC with labelling ∠BAC = α, ∠CBA = β. Triangle PQR with ∠QPR = α, ∠RQP = β, PQ marked with two small vertical dashes.
Two triangles side by side. Triangle ABC with labelling ∠BAC = α, ∠CBA = β. Triangle PQR with ∠QPR = α, ∠RQP = β, PQ marked with two small vertical dashes.