Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Three-dimensional Geometry

Question:

Two lines with direction cosines a1,b1,c1 and a2,b2,c2 are called parallel if-

Options:

a1/a2 ≠ b1/b2 ≠ c1/c2

a1/a2 = b1/b2 ≠ c1/c2

a1/a2 = b1/b2 = c1/c2

a1/a2 ≠ b1/b2 = c1/c2

Correct Answer:

a1/a2 = b1/b2 = c1/c2

Explanation:

 We know that  two lines with direction cosine a1,b1,c1 and a2,b2,c2 are called parallel if angle θ between them is equal to zero  which is possible when 

a1/a2 = b1/b2 = c1/c2