The points A(2a,4a),B(2a,6a) and C(2a+3a,5a) (when a>0) are vertices of
an obtuse angled triangle
an equilateral triangle
an isosceles obtuse angled triangle
a right angle triangle
AB=(2a−2a)2+(4a−6a)2=2a
BC=(2a+3a−2a)2+(5a−6a)2=(3a)2+a2=2a and
CA=(2a−2a−3a)2+(5a−4a)2=(3a)2+a2=2a
Since AB=BC=CA, the triangle is an equilateral.