The area of the base of the cylinder is 4 cm2, the area of the axial section is 24 cm2, what is the volume of the cylinder.
The volume of the cylinder is found by the formula:
V = SH,
where S is the area of the base, H is the height of the cylinder / length of the generatrix.
1. Since the axial section is a rectangle whose sides are equal to the diameter of the base and the length of the generatrix, we first find the diameter of the base.
The area of the circle that lies at the base of the cylinder is found by the formula:
S = πR ^ 2,
where R is the radius of this circle.
πR ^ 2 = 4;
R ^ 2 = 4 / π;
R = √4 / π = 2 / √π = 2√π / π (cm).
Then the base diameter will be equal to:
D = 2R = 2 * 2√π / π = 4√π / π (cm).
2. Let the axial section be a rectangle ABCD, then AB = CD = H, AD = BC = D = 4√π / π.
The area of a rectangle is equal to the product of its length and width, then:
Sc = H * D;
4√πH / π = 24;
4√πH = 24π;
H = 24π / 4√π;
H = 6π / √π = 6π√π / π = 6√π (cm).
3. Find the volume of the cylinder:
V = 4 * 6√π = 24√π (cm ^ 3).
Answer: V = 24√π cm ^ 3.