Answer:
8.246 units long
2sqrt(17) units long in simplest radical form
Step-by-step explanation:
Use the Pythagorean Theorem to find the missing leg length:
a^2+b^2=c^2
4^2+b^2=sqrt(84)^2
16+b^2=84
b^2=68
b=sqrt(68)
b=2sqrt(17) <-- Simplest Radical Form
b=8.246
So the third side is approximately 8.246 units long
