Work out the length X

Answer:
12.1244 or [tex]\sqrt{147}[/tex]
Step-by-step explanation:
Use the Pythagorean Theorem and solve for b^2:
7^2+b^2= 14^2
Simplify:
49+b^2= 196
Subtract 49 from both sides:
49-49+b^2= 196-49
Simplifly:
b^2= 147
Unsquare both sides:
[tex]\sqrt{b} = \sqrt{147}[/tex]