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TS EAMCET · Maths · Circle

Which of the following equations gives a circle?

  1. A \(r=2 \sin \theta\)
  2. B \(r^2 \cos 2 \theta=1\)
  3. C \(r(4 \cos \theta+5 \sin \theta)=3\)
  4. D \(5=r(1+\sqrt{2} \cos \theta)\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(r=2 \sin \theta\)

Step-by-step Solution

Detailed explanation

Now, taking option (a) i.e. \(r=2 \sin \theta\) Let \(x=r \sin \theta, y=r \cos \theta\) \(\Rightarrow \quad r^2=2 r \sin \theta\) \(\Rightarrow \quad x^2+y^2=2 y \quad\left[\because x^2+y^2=r^2\right]\) This equation represents a circle.