c) r=9,2 m
a=17,5 m

A=r×π(r+a)=9,2×3,14(9,2+17,5)=9,2×3,14×26,7=771,31 cm²
V=r²×π×m/3=9,2²×3,14×14,89/3=84,64×3,14×14,89/3=3957,31/3=1319,1 cm³

r²+m²=a²
a²-r²=m²
17,5²-9,2²=m²
306,25-84,64=m²
221,61=m²
√ 221,61 =m
14,89=m

d) r=8,6 mm
m=22,4 mm

A=r×π(r+a)=8,6×3,14(8,6+23,99)=8,6×3,14×32,59=880,06 cm²
V=r²×π×m/3=8,6²×3,14×22,4/3=73,96×3,14×22,4/3=5202,05/3=1734,02 cm³

r²+m²=a²
8,6²+22,4²=a²
73,96+501,76=a²
575,72=a²
√ 575,72 =a
23,99=a