16 and 17. area is given. A=[tex] \pi r^{2} [/tex] use this relation to find radius
18.base=2, h=3.8 so, area=(1/2)*base*h=3.8 thats option D
19. area= base*h=12*7=84 option B
20.area of trapezoid= (1/2)h(a+b) where a and b are parallel sides.
so, area=(1/2)(3)(8.9+3.3)=(1/2)(3)(12.2)=3*6.1=18.3 option D
