Mathematics · Class 11
Straight Lines
Learn Straight Lines with notes, examples, and practice questions.
2 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Coordinate geometry of lines: slope, forms of equation, angle between lines, distance from point to line, and family of lines.
Forms & Slope
Slope
m = (y₂−y₁)/(x₂−x₁) = tan θ
Point-slope
y − y₁ = m(x − x₁)
Slope-intercept
y = mx + c
General
ax + by + c = 0; slope = −a/b
Distance point to line
|ax₁+by₁+c|/√(a²+b²)
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Line through (1,2) slope 3
Equation?
- 1y−2=3(x−1)
Answer
y=3x−1
Distance from (0,0) to 3x+4y−10=0
Find.
- 1|−10|/5=2
Answer
2 units
Key Points to Remember
- ✓ Parallel lines: equal slopes
- ✓ Perpendicular: m₁m₂=−1
- ✓ Intercept form: x/a+y/b=1
Exam Tips
- • Convert to ax+by+c=0 for distance formula
- • Check vertical line (undefined slope)
Practice MCQs — Straight Lines
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
Slope of y=2x+5: