Answer:
x = 8.17
Step-by-step explanation:
We will be using pythagoras theorem:
[tex]a^{2} + b^{2} = c^{2}[/tex]
=> [tex]4.25^{2} + x^{2} = 9.21^{2}[/tex]
=> [tex]x^{2}[/tex] = 84.8241 - 18.0625 = 66.7616
=> x = [tex]\sqrt{66.7616}[/tex] = 8.17077719.. = 8.17 (3 s.f)
