D. 39
you use the pythagorean theorem which is [tex]a^{2}+b^{2} = c^{2}[/tex]
if you look at the triangle we can see that we have to find the length of the hypotenuse (BC).
so your equation will look like this:
[tex]15^{2} + 36^{2} =c^{2}[/tex]
1. [tex]15^{2} + 36^{2} =c^{2}.[/tex] (solve for [tex]15^{2} and 36 ^{2}[/tex])
2. C= 225+1296 (add)
3. C= 1521 (find the square root of 1521)
4. [tex]\sqrt{1521} = 39[/tex]
Therefore, 39 is your answer
Hope this helps!
