Here are the solutions to the geometry problems:
Problem (i):
- Given: O is the centre of circle ABC. AC is produced to D such that CD = CB. O^1=128∘.
- To prove: D^=32∘.
Step 1: Find the angle at the circumference subtended by arc AB.
∠ACB=21×O^1
∠ACB=21×128∘
∠ACB=64∘
Reason: Angle at the circumference is half the angle at the centre subtended