question_answer

Equation of a circle whose centre is origin and radius is equal to the distance between the lines \[x=1\] and \[x=-1\] is [MP PET 1984]

A)            \[{{x}^{2}}+{{y}^{2}}=1\]   

B)            \[{{x}^{2}}+{{y}^{2}}=\sqrt{2}\]

C)            \[{{x}^{2}}+{{y}^{2}}=4\]   

D)            \[{{x}^{2}}+{{y}^{2}}=-4\]

Correct Answer: C

Solution :

           Radius = 2, C (0, 0)            Equation of circle can be found from this.