Answer: A
Explanation:
This is a right triangle. In a right triangle, to know the length of sides, we can use the Pythagorean Theorem.
Pythagorean Theorem:
[tex]c^2=a^2+b^2[/tex]
Where
c is the hypotenuse (side opposite to 90 degree angle)
a and b are the two legs of the triangle
We put the known info into the formula and figure out "c", the unknown side:
[tex]\begin{gathered} c^2=a^2+b^2 \\ c^2=5^2+12^2 \\ c^2=25+144 \\ c^2=169 \\ c=\sqrt[]{169} \\ c=13 \end{gathered}[/tex]
The length of the unknown side is 13 inches
