Zaymiey

📐 Mathematics  ·  Three Dimensional Geometry  ·  JEE

The Cartesian equation of a line through (x<sub>1</sub>,y<sub>1</sub>,z<sub>1</sub>) with direction ratios a,b,c is:

Answer: (x-x 1 )/a = (y-y 1 )/b = (z-z 1 )/c.

  • A x/a = y/b = z/c, without referencing the given point
  • B ax + by + cz = 0, the plane equation form
  • C x + y + z = constant, a single linear relation
  • D (x-x<sub>1</sub>)/a = (y-y<sub>1</sub>)/b = (z-z<sub>1</sub>)/c

Correct answer: D. (x-x<sub>1</sub>)/a = (y-y<sub>1</sub>)/b = (z-z<sub>1</sub>)/c

Explanation: Symmetric (Cartesian) form: (x-x<sub>1</sub>)/a = (y-y<sub>1</sub>)/b = (z-z<sub>1</sub>)/c. Each fraction equals the parameter lambda.

zxyOP (x, y, z)

Three mutually perpendicular axes x, y, z meeting at the origin O, with a point P located by its (x, y, z) coordinates.

Concept context

Lines and planes in 3D space, direction cosines, distances, and angles

Read the full Three Dimensional Geometry notes →