Straight Lines — Syllabus
ICSE · Class 11 · Mathematics
What Straight Lines covers in ICSE Class 11 Mathematics: 4 topics, for the 2026-27 session. Part of the ICSE Class 11 Mathematics syllabus.
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Topics in Straight Lines
1. Basic Concepts from Coordinate Geometry
- Distance between two points is found using the distance formula.
- Section formula gives the coordinates of a point dividing a line segment internally in a given ratio.
- Midpoint formula is a special case of the section formula when the ratio is 1:1.
2. Slope, Inclination, and Collinearity
- Slope is defined as tan θ, where θ is the inclination of a line.
- Inclination is measured anticlockwise from the positive x-axis and satisfies 0°≤θ<180°.
- Slope of a horizontal line is 0.
3. Equation of a Line in Different Forms
- A first degree equation ax+by+c=0 represents a straight line.
- Horizontal lines are of the form y=a or y=-a and are independent of x.
- Vertical lines are of the form x=a or x=-a and are independent of y.
4. Angle Between Lines, Parallelism, Perpendicularity, and the General Equation
- The acute angle between two lines depends on their slopes.
- The obtuse angle formula uses the negative of the absolute-value expression.
- Two non-vertical lines are parallel if and only if their slopes are equal.
Key Concepts
Central concept: Straight Lines in Coordinate Geometry
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