Engineering aspirants preparing for WBJEE 2019 will get study notes including important concepts, formulae and some solved questions related to Three Dimensional Geometry. There notes are prepared by subject experts after doing the detailed analysis of the previous years’ papers and latest syllabus of WBJEE. Students generally find **2-3 questions** from this topic in the examination. With the help of these notes, students can study the following topics:

- Direction cosines,
- Direction ratio,
- Relation between the direction cosines,
- Relation between direction cosines and direction ratio,
- Vector equation of a line,
- Cartesian equation of a line passing through two points,
- Distance between two parallel lines,
- Equation of a plane,
- Condition for coplanar planes and
- Distance of a point from a plane

**WBJEE: Important Questions and Preparation Tips – Limits**

**Important Concepts:**

**Some previous years solved questions are given below:**

**Question 1:**

**Solution 1:**

Hence, the correct option is (b).

**Question 2:**

**Solution 2:**

Hence, the correct option is (c).

**Question 3:**

**Solution 3:**

When the line lies on the plane then, the direction ratios of the line must be perpendicular to the direction ratios of normal to the plane.

The line must be perpendicular to the normal to plane.

3.1 + (2 + λ) (─2) + (─1).0 = 0

Hence, the correct option is (C).

**Question 4:**

**Solution 4:**

Hence, the correct option is (b).

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