3. in a square ABCD, the diagonals AC and BD bisect at O. then triangleAOB is
a)acute angled
b)right angled
c)obtuse angled
d)equilateral
3. in a square ABCD, the diagonals AC and BD bisect at O. then triangleAOB is
a)acute angled
b)right angled
c)obtuse angled
d)equilateral