All Exams Test series for 1 year @ ₹349 only
Question

ABCD is a quadrilateral with sides AB = 9 cm, BC = 40 cm, CD = 28 cm and DA = 15 cm and one of the diagonals AC = 41 cm. Which of the following statements is/are correct ?
I. The vertices A, B, C and D of the quadrilateral lie on a circle.
II. The area of triangle ACD is \(126\text{ cm}^2\).
Select the answer using the code given below :

This question was previously asked in
CDS 2 2026 Maths Question Paper (13-Sep-2026)
The correct answer is

II only

To determine which statements are correct, we need to analyze both aspects of the question regarding the quadrilateral ABCD.

  1. Check if the vertices A, B, C, and D lie on a circle (Statement I):
    • A quadrilateral can be inscribed in a circle if and only if the opposite angles are supplementary, or according to the Ptolemy’s theorem: \( AC \cdot BD = AB \cdot CD + AD \cdot BC \).
    • Given:
      \( AB = 9 \text{ cm} \), \( BC = 40 \text{ cm} \), \( CD = 28 \text{ cm} \), \( DA = 15 \text{ cm} \), and \( AC = 41 \text{ cm} \).
    • Using Ptolemy’s theorem: \(AC \cdot BD = AB \cdot CD + AD \cdot BC\)
      To find BD, rearrange and solve:
      Assuming \( BD = x \),
      \( 41 \cdot x = 9 \cdot 28 + 15 \cdot 40 \).
      \( x = \frac{252 + 600}{41} \).
      Simplifying,
      \( x = \frac{852}{41} = 20.780 \text{ (approx)} \).
    • Since the obtained value of BD does not provide an integer, Ptolemy's theorem is not verified using this length, suggesting that ABCD is not a cyclic quadrilateral.
    • Thus, Statement I is not correct.
  2. Calculate the area of triangle ACD (Statement II):
    • To find the area of triangle ACD, we will use Heron's formula: \(s = \frac{AC + CD + DA}{2}\)
    • Calculate the semi-perimeter \( s \)\(s = \frac{41 + 28 + 15}{2} = 42 \text{ cm}\)
    • Now, applying Heron's formula: 
\(\text{Area} = \sqrt{s(s-AC)(s-CD)(s-DA)}\)\(\text{Area} = \sqrt{42(42-41)(42-28)(42-15)}\)\(= \sqrt{42 \times 1 \times 14 \times 27}\)\(= \sqrt{15876}\)\(= 126 \text{ cm}^2\)
  • Thus, Statement II is correct.

Therefore, upon analysis, the correct answer is statement II only.

Was this answer helpful?

Similar Questions

  1. In a quadrilateral ABCD, the diagonals intersect at O. Let the area of the triangle ABD be \(p\). If AO : OC = m : n, then what is the area of the triangle BCD ?
  2. ABC is a triangle right-angled at C. Let P be the midpoint of BC. If \(\text{AP} = 4\sqrt{13} \text{ cm}\) and \(\text{AB} = 20 \text{ cm}\), then what is the perimeter of the triangle ABC ?
  3. The perimeter of a right-angled isosceles triangle is 20 units. If \(\alpha\) is the area of the triangle, then
  4. The minute hand of a clock is 15 cm long and sweeps an area of \(15\pi\text{ cm}^2\) on the dial of the clock. How much angle does it describe during this period ?
  5. A square and a rectangle have the same perimeter p and their areas differ by q units. What is the square of the difference between the length and breadth of the rectangle ?
  6. The area of a rhombus is \(720\ \text{cm}^2\) and the sum of its diagonals is \(98\ \text{cm}\). What is the perimeter of the rhombus?

  7. On a circular metal plate of uniform thickness, 16 holes, each of diameter 2 cm, are made. If the plate thereby has lost one-ninth of its original weight, then what is the diameter of the plate?

  8. PQRS is a square. M is a point on PS such that PM : MS = 2 : 1 and N is a point on SR such that SN : NR = 1 : 2. If the area of triangle MQN is 10 square units, then what is the perimeter of the square?

  9. In a quadrilateral ABCD, \(\angle ABC = 90^\circ\) and \(\angle ACD = 90^\circ\). Let \(AB = p\) units, \(BC = q\) units, \(AC = r\) units, \(CD = s\) units, \(AD = t\) units, where \(p < q < r < s < t < 15\). If p, q, r, s and t are integers, then what is the area of the quadrilateral?

  10. A Question is given followed by two Statements I and II. Consider the Question and the Statements and mark the correct option.

    Question: The diagonal of a rectangle ABCD (AB > BC) is \(5\sqrt{2}\) cm. What is its perimeter?

    Statement I: Length AB is an integer.

    Statement II: Length BC is an integer.

    Which one of the following is correct in respect of the above Question and Statements?


Important Questions from 2-D Mensuration

  1. The length of a rectangular plot is $(x^2 + xy + y^2)$ m and its breadth is $(x^2 - 5xy - y^2)$ m.
    Find its perimeter, when $x = 1$ and $y = -1$.
  2. The ratio between the perimeter and breadth of a rectangle is 3: 1. If the area of the rectangle is $98 \text{ cm}^2$, find the perimeter (in cm) of the rectangle.
  3. The shorter side of a rectangle is 15 cm less than the longer side. The numerical value of its area is equal to 5 times the numerical value of its perimeter. What is the length (in cm) of its longer side?

  4. In a circle of radius 10.5 cm, if the angle of a sector is $\frac{2\pi}{3}$, then the perimeter of the sector is (in cm):
    (Take $\pi = \frac{22}{7}$)
  5. Find the circumference (in m) of the largest circle that can be inscribed in a rectangle whose dimensions are given as 114 m and 63 m.
    Take $\pi = \frac{22}{7}$
Need Expert Advice?
Test Series
CDS img
Defence
UPSC CDS 2026 Mock Test Series
536 Tests 4 Tests Free
1633 Attempts
4.3(174)
English, Hindi
More Questions from CDS

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App