Answer:
[tex] \sqrt{377} [/tex]
Step-by-step explanation:
this is a right angle triangle so you're going to use Pythagoras formula
[tex]21 {}^{2} = x {}^{2} + 8 {}^{2} [/tex]
[tex]x {}^{2} = 21 {}^{2} - {8}^{2} [/tex]
[tex]x {}^{2} = 377[/tex]
[tex]x = \sqrt{377} [/tex]
hope it helps :)
