A very good morning to you Sonia!!! Here are my workings for this question.

We will need to leave part (i) answer in exact form or at least show it as part of the working (before writing out the decimals) because we will need this exact form for part (ii), since the value to be obtained contains an exact form.

For part (ii), we cut the diagram into several pieces and compute it. Without this "hence" stipulation, we can attempt to integrate the graph with respect to y. However, we soon find that x = inverse sin y and we are unable to integrate this function in the O Level (it can be done in the A Levels though). Therefore, we have no choice but to cut the diagram into several parts to obtain the shaded area.

I hope my workings help you! Let me know if my workings are unclear and I will do my best to explain them in more detail!