Hello Candidate,

the distance between any two arbitrary points in a two dimensional plane is given by the square root of the difference modulus of x square components and y square components and adding them both.

So, in the given question the distance between the two points is equal to- √{asin60-0}^2+ {acos60-0}^2}= √a^2 sin^2(60)+ a^2 cos^(60)= a.

Hope that this Answer helps you!!