What is the area, in square units, of triangle $ABC$ in the figure shown if points $A$, $B$, $C$ and $D$ are coplanar, angle $D$ is a right angle, $AC = 13$, $AB = 15$ and $DC = 5$?

24

Step-by-step explanation:

Seeing that triangle ACD is a 5-12-13 right triangle, AD=12. Then using Pythagorean Theorem, we can calculate BD to be BD=. Thus, the area of triangle ABD is and the area of triangle ACD is . The area of triangle ABC is the difference between the two areas:

i think da answer is

d.square root of 3