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Vidaara.orgClass 9 · Mathematics
CodeVID-M09-10-CYC-01
Cyclic Quadrilaterals - Assignment
Chapter: Circles
Topic: Circles Through Three Points and Cyclic Quadrilaterals
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.
Opposite angles of a cyclic quadrilateral sum to:
  • A.$90^\circ$
  • B.$180^\circ$
  • C.$270^\circ$
  • D.$360^\circ$
2.
Through three non-collinear points passes exactly:
  • A.no circle
  • B.one circle
  • C.two circles
  • D.infinitely many
3.
The exterior angle of a cyclic quadrilateral equals the:
  • A.adjacent angle
  • B.interior opposite angle
  • C.right angle
  • D.central angle
4.
A quadrilateral is cyclic if its vertices lie on a:
  • A.line
  • B.circle
  • C.triangle
  • D.square
5.
If one angle of a cyclic quadrilateral is $80^\circ$, the opposite is:
  • A.$80^\circ$
  • B.$100^\circ$
  • C.$90^\circ$
  • D.$110^\circ$
Section B — Short Answer (2 marks) 4 × 2 = 8 marks
6.
One angle of a cyclic quadrilateral is $70^\circ$. Find the opposite angle.
7.
How many circles pass through three non-collinear points?
8.
Opposite angles of a cyclic quadrilateral are $95^\circ$ and $x$. Find $x$.
9.
The exterior angle of a cyclic quadrilateral is $100^\circ$. Find the interior opposite angle.
Section C — Short Answer (3 marks) 4 × 3 = 12 marks
10.
In cyclic quadrilateral $ABCD$, $\angle A=85^\circ$, $\angle B=95^\circ$. Find $\angle C$ and $\angle D$.
11.
Three angles of a cyclic quadrilateral (in order $A,B,C$) are $80^\circ,95^\circ,100^\circ$. Find the fourth.
12.
Can a circle pass through three collinear points?
13.
The exterior angle of a cyclic quadrilateral is $110^\circ$. Find the interior opposite angle.
Section D — Long Answer (5 marks) 2 × 5 = 10 marks
14.
In cyclic quadrilateral $ABCD$, $\angle A=(2x+4)^\circ$ and $\angle C=(3x+1)^\circ$. Find $x$ and both angles.
15.
State the result about the opposite angles of a cyclic quadrilateral.

Answer Key

Section A — Multiple Choice Questions
  1. (B) $180^\circ$
  2. (B) one circle
  3. (B) interior opposite angle
  4. (B) circle
  5. (B) $100^\circ$
Section B — Short Answer (2 marks)
  1. $110^\circ$.
  2. One.
  3. $85^\circ$.
  4. $100^\circ$.
Section C — Short Answer (3 marks)
  1. $\angle C=95^\circ,\ \angle D=85^\circ$.
  2. $\angle D=85^\circ$.
  3. No.
  4. $110^\circ$.
Section D — Long Answer (5 marks)
  1. $x=35$; $\angle A=74^\circ,\ \angle C=106^\circ$.
  2. They are supplementary: $\angle A+\angle C=180^\circ$ and $\angle B+\angle D=180^\circ$.
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