Use Pythagoras' theorem to find the length of the diagonal of a rectangle.
It is a three dimensional shape whose cross-section along the whole of its length is the same rectangle.
The volume of a rectangular prism (a shape like box)
It is rectangular.
A triangular prism has a triangular cross-section. A rectangular prism has a rectangular cross-section.
Area = length * width
It is a rectangle.
It is a rectangle which is similar to (but smaller than) the rectangular base.
They both have sides that are rectangular in shape. They both have a constant cross-sectional shape equal to the shape of the ends (triangle for a triangular prism; rectangle for a rectangular prism).
There is no formula for calculating the volume of a classroom. A classroom's volume will be calculated based upon the shape of the room. If the classroom has the shape of a cube or rectangular prism, its approximate volume can be calculated by multiplying the length by the width by the height of the room.
Rectangular Hollow Section Pipe means that shape of cross-section of RHS pipe is not round or circle but rectangular or oblong.
The cross section of cylinder along its length (parallel to the axis of symmetry has the shape of a rectangle.
The area of any rectangular shape, including the square, is the length times the breadth. Area = length x breadth