Answer:
8. 235.62 square units 9. 21.46 square units
Step-by-step explanation:
8.
Find the area of both of the circles and then subtract the area of the small circle from the area of the large one.
Remember that the formula for the area of a circle is πr^2
π5^2=78.54 units squared
π10^2=314.16 units squared
Now subtract the area of the small circle from that of the big one.
314.16-78.54=235.62 square units
9.
I'm guessing the shaded region is the area in the square that is not taken up by the semi circles because everything in that picture is white. Basically the same thing but you are subtracting the area of a circle form that of a square. They put the circle into semi circles as something of a distraction but both halves add to a full circle so just use the same formula of a circle. The radius is 5.
Square: 10^2= 100 square units
Circle: π5^2=78.54
Now subtract the circle from the square.
100-78.54=21.46 square units
