CBSE · Class 6-12

Class 11 · Mathematics (041)

Unit 9 · Class 11Mathematics (041)

Coordinate Geometry

Straight Lines

Slope, forms of a line, distance from a point to a line, angle between two lines.

Formative-only for boards

Normal form of a line
General equation of a line

Learn these concepts — they won't appear in the CBSE 2026-27 board paper.

Lessons

3 concepts

1
Slope
$m = \dfrac{y_2 - y_1}{x_2 - x_1}$ . Parallel: $m_1 = m_2$ ; perpendicular: $m_1 m_2 = -1$ .
2
Forms of a Line
Slope-intercept $y = mx + c$ ; point-slope $y - y_1 = m(x - x_1)$ ; two-point form; intercept form $\dfrac{x}{a} + \dfrac{y}{b} = 1$ .
3
Distance & Angle
Distance of $(x_0, y_0)$ from $ax + by + c = 0$ : $\dfrac{|ax_0 + by_0 + c|}{\sqrt{a^2 + b^2}}$ . Angle: $\tan\theta = \left|\dfrac{m_1 - m_2}{1 + m_1 m_2}\right|$ .

Skills to practise

Skill · medium

Straight Lines — Practice (coming soon)

Practice bank for this unit is in progress. You can still read the lessons above.