Direction Cosines & Direction Ratios
Direction cosines l, m, n satisfy l² + m² + n² = 1 (l = cos α, m = cos β, n = cos γ). Direction ratios a, b, c are proportional to direction cosines.
Grade 12th · Mathematics · Vectors and 3D Geometry
Vector Algebra & 3D Geometry: Line & Plane Equations
Master Vector Algebra & 3D Geometry: Line & Plane Equations for Grade 12th Mathematics. Includes verified formulas, core concepts, step-by-step checklists, and interactive solver tools.
Science StreamAdvanced Level
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Essential Formulas & Mathematical Definitions
Line: r = a + λ b
Shortest Distance skew lines: d = |(a2 - a1) · (b1 × b2)| / |b1 × b2|
Angle: cos θ = (b1 · b2) / (|b1||b2|)
Plane: r · n = d
Shortest Distance Between Skew Lines
Skew lines in 3D are non-parallel, non-intersecting lines lying in different planes. Shortest distance is the perpendicular projection along (b1 × b2).
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Exam Day Revision & Problem Solving Checklist
- ✓Condition for two lines to be perpendicular: a1 a2 + b1 b2 + c1 c2 = 0
- ✓Condition for two lines to be parallel: a1/a2 = b1/b2 = c1/c2
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High-Yield Exam Strategy & Scoring Tips
Step-by-Step Mark Allocation
Always state the governing principle or formula first, write given values with standard SI units, substitute clearly, and highlight the final numerical answer with units in a box for full step marking.
Common Calculation Traps
Watch for unit prefixes (cm to m, minutes to seconds, g to kg, degrees to radians). In coordinate and ray optics problems, double-check Cartesian sign conventions before computing.
Recommended Practice & Calculation Tools
Test your understanding and perform instant calculations with these free online utilities.
LaTeX Math Equation Previewer & Formatter
Live preview LaTeX math syntax with instant formatting for homework, academic papers, and Overleaf.
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Frequently Asked Exam Questions & Concept Clarifications
What is the vector equation of a line passing through two points a and b?
r = a + λ(b - a), where λ is a scalar parameter.