The edge of the cube is 10cm, Calculate the surface area of the cube.
The problem is given a cube ABCDA1B1C1D1. By definition, all edges of a cube are equal. Let us denote the length of the edge by a. By the condition of the problem:
a = 10 cm;
The task requires to find the surface area of a cube.
Formula for surface area
The cube has six faces. In our case, these are:
lower base ABCD;
upper base A1B1C1D1;
four side faces AA1B1B; BB1C1C; CC1D1D; DD1A1A.
The surface area (or total surface area) of a cube is the sum of the areas of all six faces. In a cube, all faces are squares.
The base areas are the same:
S1 = | AB | * | BC | = | A1B1 | * | B1C1 | = a ^ 2;
Areas of all side faces AA1B1B; CC1D1D; BB1C1C and DD1A1A are the same and equal:
S2 = | AB | * | AA1 | = | CD | * | CC1 | = | BC | * | BB1 | = | AD | * | AA1 | = a ^ 2;
The lateral surface area is:
Side = 4 * S2 = 4 * a ^ 2;
The total surface area is:
S = 2 * S1 + S side = 2 * a ^ 2 + 4 * a ^ 2 = 6 * a ^ 2;
Calculating surface area
Substitute the original value for a into the resulting formula:
S = 6 * a ^ 2 = 6 * 10 ^ 2 = 600 (cm ^ 2);
Note that the areas of all faces are the same and equal:
a ^ 2 = 10 ^ 2 = 100 (cm ^ 2);
Answer: the surface area of a cube is 600 cm ^ 2