## What are prisms

At the base of the prism can lie any polygon — triangle, quadrilateral, pentagon, etc. Both bases are absolutely the same, and respectively, edges by which the angles of parallel faces join together are always parallel. At the base of the correct prism lies the correct polygon, that is, one in which all sides are equal. In a straight prism, the edges between the lateral faces are perpendicular to the base. At the same time, a polygon with any number of angles can lie at the base of the straight prism. A prism whose base is a parallelogram is called a parallelepiped. Rectangle is a private case of a parallelogram. If this figure lies at the base, and the side faces are located to the base at right angles, the parallelepiped is called rectangular. The second name of this geometric body is a rectangular prism.

## How she looks

Rectangular prisms surrounded by modern man quite a lot. This is, for example, an ordinary cardboard box from under shoes, computer components, etc. Look around. Even in the room you will surely see a lot of rectangular prisms. It’s a computer case, and a bookshelf, and a refrigerator, and a closet, and a lot of other items. The shape is extremely popular mainly because it allows you to use the place as efficiently as possible, regardless of whether you design the interior or put things in cardboard boxes in front of moving.

## Rectangular prism properties

Rectangular prism have a number of specific properties. Any pair of faces can serve as its bases, since all adjacent faces are located at the same angle, and this angle is 90°. The volume and surface area of a rectangular prism is easier to calculate than any other. Take any item that has the shape of a rectangular prism. Measure its length, width, and height. To find the volume of a rectangular parallelepiped, it is enough to multiply these dimensions. That is, the formula looks like: V=A*B*h, where V is the volume, a and b are the sides of the base, h is the height that this geometric body coincides with the side edge. The base area is calculated by the formula S1=A*b. To find the area of the side surface, one must first calculate the perimeter of the base using the formula P=2 (a+b), and then multiply it by the height. The formula S2=P*H=2 (a+b) *h is obtained. To calculate the full surface of the rectangular prism, add double the base area and the side surface area. The formula is S=2s1+S2=2*A*B+2* (a+b) *h=2 [a*b+h* (a+b)]