B. X= √55
To solve this, you do the Pythagorean theorem.
a^2+b^2=c^2
Since the entire leg equals to 6, you split it in half to find the short length of the right triangle. Which would equal to 3.
3^2+b^2=8^2
9+b*2=64
Subtract 9 from both sides
b^2=55
So x would equal to √55
