Let us draw a picture to make the things more clear.
Attached is the image.
We have been given that

Therefore, we have

Now, in triangle bcd, we have

Now, in triangle acb, we have

Thus, ad is 15 cm.
4x(5x3)=(4x5)x3 the associative property basically just moves the parentheses.
Answer:
13
Step-by-step explanation:
use the Pythagorean theorem; five squared plus twelve squared is equal to the missing side squared, 25+144=169, the sqrt of 169 is 13