What is the cross-sectional area of a steel pipe with an outer diameter of 8 cm and an inner diameter of 6 cm

What is the cross-sectional area of a steel pipe with an outer diameter of 8 cm and an inner diameter of 6 cm

4 * 4 π - 3 * 3 π = 7 π cm2

A kind of round steel tube, the outer diameter is 8 cm, the inner diameter is 4 cm. What is its cross-sectional area in square centimeter
Please, 3Q as long as the formula

The outer diameter is 8 cm and the inner diameter is 4 cm
So outer radius = 8 △ 2 = 4cm, inner radius = 4 △ 2 = 2cm
Cross sectional area = 3.14 × (4 × 4-2 × 2) = 37.68 square centimeter

The cross section of a steel pipe is a ring. The diameter of its inner circle is 8 cm and the diameter of its outer circle is 10 cm. How many square centimeters is the cross section area of this steel pipe

The area of the outer circle minus the area of the inner circle is the area of the cross section
Inner circle: R1 = 4cm
Outer circle: R2 = 5cm
πr2^2-πr1^2=9π≈28.27cm^2

The cross section of a steel pipe is annular, the radius of the inner circle is 5cm, and the diameter of the outer circle is 8cm?
The other answers are = (8 ^ 2-5 ^ 2) * π = 39 π ≈ 122.46, but don't you mean the diameter of the outer circle is 8cm? Do you want to find the radius if you don't divide 8 by 2?

The answer to this question should be [5 ^ 2 - (8 / 2) ^ 2] × π = 9, π = 28.26