Question

find the co-ordinates of points C and D

Answer 1

The answer is (C) .

Ans.
Triangle ABC is equilateral .
i.e., AB = BC = AC

Now , AB = 2a ( by distance formula )
i.e., BC = 2a .........(1)

Now , OB = a ( by distance formula ).....(2)

In triangle OBC ;
BC^2 = OB^2 + OC^2 (Pythagoras Theorem )
(2a)^2 = (a)^2 + OC^2
3(a^2) = OC^2
i.e., OC = a(root3)

i.e., coordinates of C = (0,+a(root3))

Similarly ;
coordinates of D = (0,-a(root3)) ....(because it is in the negative side of y-axis)


:)