數學題，求角度，急！！?

(a) ∠BAC=∠BDC=54⁰　(∠ in the same segment)
∠CAD=110⁰-54⁰=56⁰

(b) ∠BCD+110⁰=180⁰　(opp.∠s, cyclic quad.)
∴ ∠BCD=70⁰
From ΔPCD, 86⁰=∠PCD+54⁰　　(ext.∠ of Δ) 
　　　　=>∠PCD=32⁰
∴ ∠BCA=70⁰-32⁰=38⁰

(c) ∠ subtended from arcs AB,BC,CD and DA are:
　　　　　　　　　38⁰,54⁰,56⁰ and 32⁰ respectively.
∴ longest arc = arc CD
& shortest arc = arc DA