**Characteristics of Beams –** The existence of objects around us indirectly describes the shape of the geometric shape. *Yep* , build a room that is included in the material in mathematics. Does *Sinaumed’s* still remember the material?

For example, the shape of a block shape is like a wardrobe that we often use to store our clothes, be it uniforms or casual clothes.

Try *Sinaumed’s* to remember, what are *the* spatial shapes ? Are there only blocks?

Of course not. There are many spatial structures, namely cubes, blocks, tubes, prisms, and so on.

Then, does *Sinaumed’s* know about the characteristics of a rectangular cuboid? What’s the difference between a block shape and other shapes?

In order for *Sinaumed’s* to know the characteristics of a rectangular cuboid, *let’s* look at the following explanation!

## Characteristics of Building Block Space

The beam is a geometric shape that is almost the same as a cube, but the beam has longer edges. Well, here are the characteristics of the beam!

### 1. Has 6 sides

The side of a beam becomes the boundary between the beam and three pairs of sides that have the same shape and size when facing each other.

A block must have 6 square or rectangular sides. These sides are on the left and right, up and down, and front and back.

Based on the example of the beam image, the 6 sides are:

- Left side and right side = ADHE = BCGF
- Base (bottom) and top = ABCD = EFGH
- Front side and back side = ABFE = DCGH

### 2. Has 12 ribs

The rib is the line that intersects the two sides of the beam. The ribs on this beam must be parallel and have the same length. If you notice, the ribs are like a building block.

A beam has 12 ribs, consisting of 4 long, 4 wide, and 4 high. If you pay attention to the example of the previous beam image, then the 12 ribs are:

- 4 long ribs = AB = DC = EF = HG
- 4 wide ribs = AD = BC = EH = FG
- 4 high ribs = AE = BF = CG = DH

### 3. It has 12 diagonal fields

A plane diagonal can also be called a side diagonal, namely a line segment that connects two opposite corner points on each plane or side of the beam.

Previously, it was explained that the beam has 6 sides, therefore the diagonals of the fields total 12. If you pay attention to the example of the image of the beam, the 12 diagonals of the fields are:

- Diagonals AC = EG
- Diagonals BD = FH
- Diagonals AH = BG
- Diagonals CF = DE
- Diagonals AF = DG
- Diagonals BE = CH

### 4. Has 8 corner points

The corner points on each beam are 8 pieces. The corner points are formed by the meeting of every 3 ribs of the beam.

If you pay attention to the example of the previous beam image, then the 8 corner points are points A, B, C, D, E, F, G, and H.

### 5. It has 4 diagonal spaces

The space diagonal is a line that connects two corner points facing each other in one space. If you pay attention again to the example of the beam image, then the 4 diagonals of the space are:

- AG line segment
- HB line segment
- DF line segment
- CE line segment

### 6. Has 6 diagonal fields

The diagonal field is different from the field diagonal previously described, *Sinaumed’s…*

A diagonal plane is a plane bounded by two edges and two diagonals. Well, on a beam, there are 6 diagonal fields.

If you pay attention to the example of a beam image, the 6 diagonal fields are:

- ACGE = BDHF diagonal plane
- ABGH = DCFE diagonal plane
- Diagonal plane BCHE = ADGF

### 7. It has both surface area and volume

As with other geometric figures, a block also has a surface area and volume. Volume is related to how wide the room is in a geometric shape.

To determine the surface area and volume of a cuboid, it can be found using a certain formula. The formula for calculating the surface area of a beam is:

**2 x (pl + lt + pt)**

p = length of the beam

l = beam width

t = height of the beam

Meanwhile, to determine the volume contained in a beam, it also has a certain formula, namely:

**V = pxlxt**

p = length of the beam

l = beam width

t = height of the beam

## Example questions and discussion

- A cuboid has a length of 12 cm, a width of 7 cm and a height of 5 cm. What is the surface area of the block?

**Answer:**

**L = 2 x (pl + lt + pt)**

**L = 2 x (12.7 + 7.5 + 12.5)**

**L = 2 x (84 + 35 + 60)**

**L = 2 x 179**

**L = 358 cm²**

- A cuboid has a length of 12 cm, a width of 7 cm and a height of 5 cm. What is the volume of the block?

**Answer:**

**V = pxlxt**

**V = 12 x 7 x 5**

**V = 420 cm²**

Well, that’s the characteristics of building blocks. Does *Sinaumed’s* already understand the geometric shapes of blocks and the formulas for calculating the area and volume of space? In order for *Sinaumed’s* to better understand the formula, you can do this by practicing calculating the area and volume of a block in the problem practice book.