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Vidaara.orgClass 11 · Mathematics
CodeVID-M11-09-SLP-01
Slope & Angle Between Lines — Assignment
Chapter: Straight Lines
Topic: Slope of a Line and Angle Between Two Lines
Maximum Marks: 35
Time: 75 minutes
Name: ____________________ Roll No.: __________ Date: ____________

General Instructions

  • All questions are compulsory.
  • Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
  • Show all working for Sections B, C and D. Only final answers are given at the end — for full solutions, raise your doubts with your teacher.
Section A — Multiple Choice Questions 5 × 1 = 5 marks
1.
The slope of a horizontal line is:
  • A.$0$
  • B.undefined
  • C.$1$
  • D.$\infty$
2.
The slope of the line through $(1,2)$ and $(3,6)$ is:
  • A.$1$
  • B.$2$
  • C.$3$
  • D.$\tfrac12$
3.
Two lines are perpendicular if:
  • A.$m_1=m_2$
  • B.$m_1m_2=-1$
  • C.$m_1+m_2=1$
  • D.$m_1m_2=1$
4.
The slope of $y=-3x+1$ is:
  • A.$1$
  • B.$-3$
  • C.$3$
  • D.$-1$
5.
The slope of a vertical line is:
  • A.$0$
  • B.$1$
  • C.undefined
  • D.$-1$
Section B — Short Answer (2 marks) 4 × 2 = 8 marks
6.
Find the slope of the line through $(2,3)$ and $(4,7)$.
7.
Find the slope of $2x+3y=6$.
8.
Are $y=2x+1$ and $y=2x-5$ parallel?
9.
Find the slope of a line perpendicular to $y=3x$.
Section C — Short Answer (3 marks) 4 × 3 = 12 marks
10.
Find the angle between two lines with slopes $1$ and $0$.
11.
Find the slope of a line making $60^\circ$ with the positive x-axis.
12.
Show that $2x+3y=5$ and $3x-2y=7$ are perpendicular.
13.
Find $k$ if $y=kx$ and $y=2x+1$ are parallel.
Section D — Long Answer (5 marks) 2 × 5 = 10 marks
14.
Find the angle between the lines $\sqrt3\,x+y=1$ and $x+\sqrt3\,y=1$.
15.
If the points $A(1,2),\ B(3,k),\ C(5,8)$ are collinear, find $k$.

Answer Key

Section A — Multiple Choice Questions
  1. (A) $0$
  2. (B) $2$
  3. (B) $m_1m_2=-1$
  4. (B) $-3$
  5. (C) undefined
Section B — Short Answer (2 marks)
  1. $2$.
  2. $-\tfrac23$.
  3. Yes.
  4. $-\tfrac13$.
Section C — Short Answer (3 marks)
  1. $45^\circ$.
  2. $\sqrt3$.
  3. Slopes $-\tfrac23$ and $\tfrac32$; product $=-1$, so perpendicular.
  4. $k=2$.
Section D — Long Answer (5 marks)
  1. $30^\circ$.
  2. $k=5$.
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