Sigma Percentile
JEE Main 2024 (29 Jan Shift 2)
LEVELJEE Main

Animated Solution for Mathematics - Straight Lines: The distance of the point from the line , measured parallel to the line , is equal to

Select Answer:

Visualized Solution

Visualizing the Problem

  • Given Point:
  • Target Line
  • Direction Line
  • Goal: Find distance from to measured parallel to .

Finding the Direction Angle

  • Equation of direction line :
  • Rearranging to :
  • Slope
  • Therefore,

The Parametric Tool

  • Using Parametric Form for point at distance from

Raw Setup for Point

  • Substitute and
  • Let this point be

Substitution into Target Line

  • Point lies on
  • Equation of :
  • Substitute into :

Expanding the Equation

  • Expanding the terms carefully:

Grouping and Simplifying

  • Combine constant terms:
  • Combine terms:
  • Simplified Equation:

Isolating

  • Take common denominator for term:
  • Move constant to RHS:
  • Solve for :
  • Absorb negative sign:

Rationalizing the Denominator

  • Multiply numerator and denominator by conjugate:
  • Denominator becomes:

The Final Answer

  • Simplify the fraction:
  • Expand to get final form:
  • Rearranging gives:
  • This matches Option 3.

The Sigma Insight: Various Forms of Equations of a Line

Solution Diagram

The Geometry of the Path

Imagine you are standing at the point on a vast coordinate plane. You have a destination—a target line defined by the equation .
If you were a bird, you would fly the shortest path, dropping perpendicularly onto the line. But you are not a bird; you are a traveler constrained to a specific road. You must walk parallel to the line .
This constraint changes everything. It turns a simple distance problem into a beautiful exercise in parametric geometry.

Phase 1

Finding Your Compass
Before we take a single step, we must know our heading. The line that dictates our direction is .
To understand its tilt, we rearrange it into the slope-intercept form, . This gives us . The slope is .
We know that the slope of a line is the tangent of the angle it makes with the positive x-axis. So, . Recalling our trigonometry, we identify that . Our path is set; we are walking at a angle relative to the horizontal.

Phase 2

The Parametric Bridge
Now, how do we mathematically describe our journey? We use the parametric form of a straight line. If we start at and walk a distance at an angle , any point on our path is given by the elegant equations:
Substituting our starting point and our angle , we get:
This is the bridge between our movement and the target line. Every point on our path is now defined by the distance we have traveled.

Phase 3

The Intersection
Our destination is the target line . Since our point must lie on this line, its coordinates must satisfy the equation.
We substitute our parametric expressions for and into the line equation:
Now, we expand carefully. Precision is key here. We get:
Grouping the constants and the -terms, we have:

Phase 4

The Final Calculation
We are almost there. Isolating , we find:
To finish, we rationalize the denominator by multiplying the numerator and denominator by the conjugate, :
Watch the magic happen: divided by is exactly . Thus, .
We have arrived. The distance is . It is a beautiful result, born from the simple act of following a path.

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