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Vidaara.orgClass 7 · Mathematics
CodeVID-M07-08-TRI-01
Triangle Angle Sum & Exterior Angle - Assignment
Chapter: Angles in Parallel Lines & Triangles
Topic: Triangle Angle Sum & Exterior Angle Theorem
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 angle sum of a triangle is:
  • A.$90^\circ$
  • B.$180^\circ$
  • C.$270^\circ$
  • D.$360^\circ$
2.
An exterior angle equals the sum of the two:
  • A.adjacent angles
  • B.opposite interior angles
  • C.right angles
  • D.exterior angles
3.
An exterior angle is ___ either opposite interior angle.
  • A.equal to
  • B.greater than
  • C.less than
  • D.half of
4.
The three exterior angles of a triangle sum to:
  • A.$180^\circ$
  • B.$360^\circ$
  • C.$270^\circ$
  • D.$90^\circ$
5.
If two angles are $50^\circ$ and $60^\circ$, the third is:
  • A.$60^\circ$
  • B.$70^\circ$
  • C.$80^\circ$
  • D.$90^\circ$
Section B — Short Answer (2 marks) 4 × 2 = 8 marks
6.
Two angles are $40^\circ$ and $75^\circ$. Find the third.
7.
An exterior angle is $120^\circ$. The two opposite interior angles sum to:
8.
Each angle of an equilateral triangle is:
9.
The exterior angle at a vertex with interior $70^\circ$ is:
Section C — Short Answer (3 marks) 4 × 3 = 12 marks
10.
An exterior angle is $110^\circ$ and one opposite interior angle is $45^\circ$. Find the other.
11.
The angles of a triangle are in ratio $2:3:4$. Find them.
12.
Two angles are equal and the third is $80^\circ$. Find each equal angle.
13.
An exterior angle is $130^\circ$. Find the adjacent interior angle.
Section D — Long Answer (5 marks) 2 × 5 = 10 marks
14.
The angles of a triangle are $x,\ (x+10),\ (x+20)$. Find all three.
15.
An exterior angle of a triangle is $125^\circ$ and the two opposite interior angles are in ratio $2:3$. Find both interior angles.

Answer Key

Section A — Multiple Choice Questions
  1. (B) $180^\circ$
  2. (B) opposite interior angles
  3. (B) greater than
  4. (B) $360^\circ$
  5. (B) $70^\circ$
Section B — Short Answer (2 marks)
  1. $65^\circ$.
  2. $120^\circ$.
  3. $60^\circ$.
  4. $110^\circ$.
Section C — Short Answer (3 marks)
  1. $65^\circ$.
  2. $40^\circ, 60^\circ, 80^\circ$.
  3. $50^\circ$.
  4. $50^\circ$.
Section D — Long Answer (5 marks)
  1. $50^\circ, 60^\circ, 70^\circ$.
  2. $50^\circ$ and $75^\circ$.
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