In triangle ABC, AB = AC. Point P lies on line AB such that CP = BC. If angle APC = 116 degrees, what is angle ACP(in degrees)?
This is the diagram.
Note that ∠BPC=180∘−116∘=64∘.
Since BC = CP, ∠PBC=64∘.
Considering the interior angle sum of △BPC gives ∠PCB=52∘.
Since AB = AC, ∠ACB=∠ABC=∠PBC=64∘.
Therefore, ∠ACP=∠ACB−∠PCB=64∘−52∘=12∘.