Here's a step-by-step solution to the problem:
Part (a): Express, giving reasons, each of the following angles in terms of x.
Given that S1=x, which refers to ∠TSP=x.
i) ∠O1
Step 1: Identify ∠O1.
From the diagram, ∠O1 is ∠SOT. This is the angle subtended by arc ST at the center.
Step 2: Relate ∠SOT to an angle at the circumference.
The angle subtended by arc ST at the circumference is ∠SPT.
The angle at the center is twice the angle at the circumference subtended by the same arc.