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ICSE Class 10 Mathematics Question 23 of 49

Multiple-Choice Questions — Question 23

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Question 23

In the given figure line l1 is a parallel to line l2. If line l3 is perpendicular to line l1, then the slopes of lines l2 and l3 respectively are :

  1. 1, 1

  2. -1, -1

  3. 1, -1

  4. -1, 1

In the given figure line l1 is a parallel to line l2. If line l3 is perpendicular to line l1, then the slopes of lines l2 and l3 respectively are : Maths Competency Focused Practice Questions Class 10 Solutions.
Answer

Slope of line l1 = tan 45° = 1.

We know that,

Slope of parallel lines are equal.

Slope of line l2 = Slope of line l1 = 1.

We know that,

Product of slope of perpendicular lines is equal to -1.

⇒ Slope of line l2 × Slope of line l3 = -1

⇒ 1 × Slope of line l3 = -1

⇒ Slope of line l3 = -1.

Hence, Option 3 is the correct option.