Descriptive geometry is quite a different and useful branch of mathematics. It was discovered in 1765 by Gaspard Monge who was at that time a draftsman in military. He got his findings published, which were found to be of great importance at that time. He is therefore known as "the father of descriptive geometry".
Descriptive geometry deals with two-dimension projection of a three-dimensional image. This branch of mathematices has now become an important part architectural drawing and many other areas. In this page, we shall go little ahead and learn about descriptive geometry and techniques involved in it.

Descriptive geometry is actually the study of the geometry of three-dimensional shapes. It includes projecting three-dimensional objects onto the two-dimensional plane. There are different kinds of objects surrounded by us. You will notice that most of them are three dimensional. In descriptive geometry, we study about the two dimensional projection of a solid or 3D figure from different angles.
Following images are the examples of representation of a three-dimensional image from different angles onto a plane surface:
Descriptive Geometry
Gaspard Monge developed different procedures and techniques for solving various geometric problems related to solid geometry. Descriptive geometry is named so, since it provides a detailed description about a solid image and solve difficult geometrical problems.
There is a vast application of descriptive geometry in many areas. It is quite useful in the field of architecture where everything is based upon three-dimensional drawings.

 Descriptive geometry is an essential part of architectural drawing.

Applied descriptive geometry is also very useful in the field of engineering and technology. Descriptive geometry is very important for engineering students to study.

 More importantly, in the disciplines like: mechanical, industrial, marine, civil, plastic, mining, piping etc.

The techniques and tools of descriptive geometry are applied to different individual fields in order to solve various practical problems.

Descriptive geometry is also used in field of media and entertainment.

The areas such as : graphics and animation, descriptive geometry is quite commonly used.

It is useful in various other newer fields of study, like: computer programming, web designing, industrial chemistry etc.
There are different types of problems in higher-level mathematics that uses the concepts and techniques of descriptive geometry. 
Some of the important ones that are commonly used in context with lines and plane, are given below :
1) Finding actual length of line.

2) Determining true size or area of a surface.

3) Giving three different views of a shape.

4) Showing intersection of two different surfaces.

5) Giving point view of a line.

6) Showing line view of a surface.

7) Determining shortest distance between one line to another.

8) Finding dihedral angle between two surface when they are intersecting.
There are many more other types of problems that can be solved and analyzed using descriptive geometry.