Surface area of the top

A cylinder is three times as high as it is wide. The length of the cylinder diagonal is 20 cm. Find the exact surface area of the top of the cylinder.

Correct answer:

S =  31.4159 cm2

Step-by-step explanation:

u=20 cm h = 3D u2 = h2 + D2 u2 = 9D2 + D2 D=9+1u=9+120=2 10 cm6.3246 cm r=D/2=6.3246/2=10 cm3.1623 cm h=3 D=3 6.3246=6 10 cm18.9737 cm u2=h2+D2=18.97372+6.32462=20 cm u=u2 (check  ok) S=π r2=3.1416 3.1623231.4159 cm2 cm2 S = 10 pi



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