This chapter has three sections. In this chapter, we will understand the use of coordinates to study geometry in three dimensions. The first section “Basic formulae” deals with formulae like Distance formula, Section formula, Direction cosines and Direction ratios etc. Three dimensional coordinate axes will divide the space into eight compartments known as octants. The direction cosines of a (directed) line are the cosines of the angles which the line makes with the positive direction of the coordinate axes. The section two deals with Plane. In this section, we will learn how to write the equation of a plane in three dimensional coordinates form. Three non collinear points are sufficient to uniquely determine the plane passing through them. The section three deals with Straight line and in this, we will learn how to write the equation for a straight line in three dimensional coordinate form. We will further learn about Unsymmetrical form of the equation of a line and Symmetrical form of the equation of a line. At the end of this section, we have a series of exercises to test your understanding of this chapter, solved examples, previous years’ IIT JEE questions pertaining to this chapter.

In addition to preparing for the JEE mains and advanced exams, Cuemath Founder Manan Khurma's study material is helpful for students who are appearing for CBSE, ICSE and other State board exams.

## Basics of Three Dimensional Geometry

## Equations of Three Dimensional Planes and Lines