Внешний диаметр полого шара равен 16 см. Толщина стенок 2 см Найти объем материала, из которого изготовлен шар.

1239.25 cm³

Step-by-step explanation:

Outer diameter 16 cm

⇒ R= 8 cm

Inner radius  

⇒ r= R- 2= 6 cm

The volume of the wall of 2 cm thickness:

⇒ 4/3πR³- 4/3πr³= 4/3*3.14*(8³-6³)= 1239.25 cm³

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

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step-by-step explanation: