(Worth 50 points. Don't post your answer unless you have good ideas) Solve the following problem:
Which triangles are similar ?

Answer: ΔABC ≅ ΔADB
Step-by-step explanation:
In order to be similar, they must have the same angles.
ΔABC ΔADB ΔDBC
∠A = 180 - (2a + b) ∠A = 180 - (2a + b) ∠D = 180 - (a + b)
∠B = a + b ∠D = a + b ∠B = b
∠C = a ∠B = a ∠C = a
ΔABC and ΔADB have the same angles so they are similar.