Step 1: find the area of the full circle:
Step 2: ignoring the triangle, what fraction of the circle are we actually looking at?
So one third of the area calculated in Step 1 is 37.6992228431.
Step 3: What is the area of the triangle?
Step 3A: Height of traingle:
Luckily, we have an isosceles triangle here so we can turn it into two right angles triangles, literally by cutting it in half.
If you look at my terrible drawing attached, we can use trigonometry to find the height of the triangle (the red line).
Rearrange:
Putting our numbers in:
Step 3B: Area of triangle from height and radius:
Sticking to our two halfs, we now have the area of a right-angled triangle:
Mutliplied by 2 because we split the big triangle into 2:
Step 4: Finding the area of the blue region:
Remember we got the area for the blue region plus the triangle by doing the area for the full circle then just finding the fraction of it? If we take the are of the triangle away from that we will just get the are of the blue region!
Lets round that last number to the nearest tenth and put our units on:
Additional Info:
These questions are very long winded so you were absolutely right to ask for steps, and make sure you write down all the steps you have to do before you do them like I did with headings, so that you don't get lost.