Find the midpoint of ab: a(3,-8) B(-15,-8)

Nikolas calculated the volume of the prism. his work is shown below.

Circle d circumscribes abc and abe. which statements about the triangles are true? statement i: the perpendicular bisectors of abc intersect at the same point as those of abe. statement ii: the distance from c to d is the same as the distance from d to e. statement iii: bisects cde. statement iv: the angle bisectors of abc intersect at the same point as those of abe. a. i only b. i and ii c. ii and iv d. i and iii e. iii and iv

For what values of a is the sum of the fractions 2a−1 / 4 and a−1 /3 positive?