In this question is just a matter of working outside in.
we know the radius that is 5.
Calculate the area of the circle \(C= \pi r^2=\pi·5^2≈78.53982\) Therefore we assume for easier calculation that the area is
79The entire area where we do have the triangle is half that so is \(39.5\)
The radius 5 is also the side of the triangle and the height is also 5 because is also the radius 5. So the area of the triangle is \(\frac{b*h}{2}=\frac{5*5}{2}=12.5\)
The two areas outside the triangle BUT inside the half of the circle we are considering is \(39.5\) (area half of the circle) minus the area of the triangle \(12.5=39.5-12.5= 27\)
we need the shaded region which is half the sum of the two areas \(\frac{27}{2}=13.5\)
The answer is \(\approx 13.5\)
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