Question

Question was provided via image upload.

Explanation:

Step1: Apply Pythagorean theorem

In a right - triangle, $a^{2}=b^{2}+c^{2}$, where $b = 12$ and $c = 16$. So $a=\sqrt{12^{2}+16^{2}}$.

Step2: Calculate squares

$12^{2}=144$ and $16^{2}=256$. Then $12^{2}+16^{2}=144 + 256=400$.

Step3: Calculate square - root

$a=\sqrt{400}=20$.

Answer:

$20$ cm