Mario is writing a coordinate proof to show that the perpendicular bisector of an isosceles triangle's base divides it into two triangles of equal area. a triangle is graphed on a coordinate plane. the vertices of triangle are labeled as a, b and c. the vertex labeled as a lies on begin ordered pair 0 comma 0 end ordered pair. the vertex labeled as b lies on begin ordered pair x comma y end ordered pair. the vertex labeled as c lies on begin ordered pair 2 x comma 0 end ordered pair. point d lies on side a c. an altitude is drawn from point b to point d. enter your answers in the boxes to complete mario's proof. since a perpendicular bisector bisects a segment, the coordinates of d are ( , ). in △bcd, the length of the base is and the height is y. so an expression for the area of △bcd is 12xy . in △abd, the length of the base is and the height is . so an expression for the area of △abd is 12xy . comparing the two areas shows that the perpendicular bisector of an isosceles triangle divides the triangle into two triangles of equal area.