Question

The parametric equations of the circle $4x^2+4y^2=25$ is

• A. $x=\frac{5}{2}\cos \theta ,y=\frac{3}{2}\sin \theta$
• B. $x=\frac{5}{2}\cos \theta ,y=\frac{5}{2}\sin \theta$
• C. $x=\frac{7}{2}\cos \theta ,y=\frac{7}{2}\sin \theta$
• D. $x=\frac{1}{2}\cos \theta ,y=\frac{1}{2}\sin \theta$

Answer 1

The correct option is B $x=\frac{5}{2}\cos \theta ,y=\frac{5}{2}\sin \theta$

$x^2+y^2=\frac{25}{4}={\left(\frac{5}{2}\right)}^2$

So, $r=\frac{5}{2}$

Parametric equation will be,

$x=r\cos \theta ,y=r\sin \theta$

$x=\frac{5}{2}\cos \theta ,y=\frac{5}{2}\sin \theta$