The total length of all the edges of the cube is 840 cm. Calculate the area of one face of the cube.

The total length of all the edges of the cube is 840 cm. Calculate the area of one face of the cube. Calculate the total area of all the faces of the cube.

Brief entry:
Cube;
L = 840 cm.;
S face =?;
S total =?
Solution:
1) There are 12 equal faces in a cube.
Then the length of one face is equal to the quotient of dividing the length of all edges of the cube by the number of edges.
l = L / 12;
l = 840/12 = 70 (see);
2) The face of the cube is a square, then the area of one face is equal to the square of the face.
S face = l²;
S faces = 70² = 4900 (sq. Cm.);
3) A cube has 6 faces, then the area of all faces is equal to the product of the area of one face by the number of such faces.
S total = 6 * S faces = 6 * 4900 = 29,400 (sq. Cm.);
Answer: S edge = 4900 sq. cm.; S total = 29 400 sq. cm.;