Answer:
329.29... mm²
Explanation:
it is the area of the circle minus the area of the white triangle.
what we see as dotted line is on one hand the radius of the circle but also the height of the triangle.
we know the area of a circle is
pi×r²
and the area of a triangle is
baseline×height/2
the baseline of the triangle is clearly the diameter (=2×r) of the circle.
so, we have everything and need only to do the calculations.
the area of the shaded figure is
As = pi×(12.4)² - (2×12.4)×12.4/2 = pi×(12.4)² - 12.4×12.4 =
= pi×(12.4)² - (12.4)² = (pi-1)×(12.4)² = 329.29... mm²