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📐 Mathematics  ·  Class 12  ·  JEE

Three Dimensional Geometry - Practice Questions with Answers

68 free MCQs on Three Dimensional Geometry, each with its own worked answer and explanation. Lines and planes in 3D space, direction cosines, distances, and angles

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68 practice questions on Three Dimensional Geometry, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Three Dimensional Geometry notes.

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.

Easy - 20 questions

Q1.

Direction cosines of a line are the cosines of angles made with the:

  • A xy, yz and xz planes
  • B x, y and z axes
  • C x-axis only
  • D Origin

Q2.

For direction cosines l, m, n of a line:

  • A l + m + n = 1
  • B lmn = 1
  • C l<sup>2</sup> + m<sup>2</sup> + n<sup>2</sup> = 1
  • D l<sup>2</sup> + m<sup>2</sup> + n<sup>2</sup> = 0

Q3.

The direction ratios of a line are proportional to its:

  • A Coordinates only
  • B Intercepts
  • C Slopes
  • D Direction cosines

Q4.

The equation of the XY-plane is:

  • A z = 0
  • B x = 0
  • C y = 0
  • D x + y = 0

Q5.

The distance from the origin to point P(a, b, c) is:

  • A a + b + c
  • B sqrt(a + b + c)
  • C a<sup>2</sup> + b<sup>2</sup> + c<sup>2</sup>
  • D sqrt(a<sup>2</sup> + b<sup>2</sup> + c<sup>2</sup>)

Q6.

The vector equation of a line through point A (position vector a) with direction vector b is:

  • A r = b + lambda*a
  • B r = a + lambda*b
  • C r = lambda*(a + b)
  • D r = a*b

Q7.

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:

  • 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

Q8.

The general equation of a plane is of the form:

  • A ax + by + cz + d = 0
  • B ax + by = 0
  • C ax<sup>2</sup> + by<sup>2</sup> + cz<sup>2</sup> = 0
  • D x/a = y/b = z/c

Q9.

Two lines in 3D that do not intersect and are not parallel are called:

  • A Coincident lines
  • B Perpendicular lines
  • C Coplanar lines
  • D Skew lines

Q10.

The equation of the x-axis in 3D is:

  • A y = 0, z = 0
  • B x = 0, z = 0
  • C x = 0, y = 0
  • D y = z = x = 0

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