*Note that the circumference of a circle is 2*pi*r and the area is pi*r²*
10) If the circumference is 11pi, 11 = 2*r. This means that r (radius) is 5.5. The diameter is twice the radius so it is 5.5*2 or 11.
11) If the measure of the angle is 100° and the radius is 9 (diameter divided by 2), the length of the arc is 100/360 * 2 * pi * r. If r is 9, the expression will look like this: 100/360 * 2 * pi * 9, which is 5pi. 5pi can also be expressed as
12) area = pi*1.5²→ area = 2.25pi→ area = 7.1m
13) 24/2 = radius→ 12 = radius→ area = pi*12²→ area = 144pi→ area = 452.4m
14) The area of the smaller sector is pi*19²*37/360, or 116.6cm. The area of the larger sector is pi*19²*323/360 (I got 323 because 360 - 37 = 323) which equals 1017.6cm
15) The area of the smaller sector is pi*10²*128/360 or 111.7cm. The area of the larger sector is pi*10²*232/360 (I got 232 because 360 - 128 = 232) which equals 202.5cm
I hope this helps!