### Mathematics Class XI

Unit-I: Sets and Functions
Chapter 1: Sets
Unit-II: Algebra
Chapter 5: Binomial Theorem
Chapter 6: Sequence and Series
Unit-III: Coordinate Geometry
Chapter 1: Straight Lines
Chapter 2: Conic Sections
Unit-IV: Calculus
Unit-V: Mathematical Reasoning
Unit-VI: Statistics and Probability
Chapter 1: Statistics
Chapter 2: Probability

# Inclination of a line

Inclination of a line is a real number as defined below:

(i) If a line is parallel to – axis or coincides with -axis then (ii) If a line is not parallel to -axis  then let it intersect -axis at a point .

Inclination of is given by (iii) Inclination of or is defined as the inclination of Note: If is the inclination of a line then . Parallel lines have same inclination and conversely. Inclination of perpendicular line differ by . Inclination is essentially an angle-measure. The only difference is that inclination can be zero, where as angle-measure can not be zero.

The slope of a non-vertical line is given by , where is the inclination of the line.

Note: Inclination ,  but slope . Slope of a vertical line is not defined. Slope of a line is positive, zero or negative according as the inclination of the line is less than , equal to or greater than respectively. It is obvious that slope of a line is the ration of its rise or fall to its run A line with positive slope looks like rising where a line with negative slope looks like falling as we move from left to right along the line.  Positive Slope: