Answer:
Explanation:
The idea here is to find the area of the circle and then subtract from it the area of the triangle. That will give you the area of what's left in the circle (the shaded part). The area of a circle is:
so
where 12.4 is the radius.
rounded to the nearest tenth. I used 3.14 for pi.
Now for the area of the triangle. The formula is
where h is the height of 12.4 and the base is the diameter which is 12.4 * 2 = 24.8
so

Now subtract the triangle's area from the circle's area:
482.81 - 153.76 = 329.05 mm²