find the missing side of the triangle

Answer:
x = 2[tex]\sqrt{5}[/tex]
Step-by-step explanation:
2² + 4² = x²
4 + 16 = x²
[tex]\sqrt{x^2}[/tex] = [tex]\sqrt{20}[/tex]
x = [tex]\sqrt{2^2}[/tex] × [tex]\sqrt{5}[/tex]
x = 2[tex]\sqrt{5}[/tex]