Answer:
C.13
Step-by-step explanation:
D is a midpoint, which means that AD=DB= 1/2 AB = 1/2 (24) = 12
Using Pythagorean theorem we know that CD^2+DB^2=CB^2
That means that 5^2+12^2=CB^2
25+144=169
169=13^2
CB=13
a=CB=13
