Which are the lengths of the sides of right triangle RST?

Answer: C
Step-by-step explanation:
[tex]a^{2}[/tex] + [tex]b^{2}[/tex] = [tex]c^{2}[/tex]
121 + 324 = 455
Therefore,
[tex]\sqrt{121}[/tex] + [tex]\sqrt{324}[/tex] = [tex]\sqrt{455}[/tex]
11, 18, [tex]\sqrt{455}[/tex] which is also 21.33