Solve
-A Balloon Is Secured to Rope That Is Staked $120 \mathrm { ft }$

Solve.
-A balloon is secured to rope that is staked to the ground. A breeze blows the balloon so that the rope is taut while the balloon is directly above a flag pole that is 30 feet from where the rope is staked down. Find the length of the rope if the altitude of the balloon is 90 feet.

A) $120 \mathrm { ft }$
B) $20 \sqrt { 3 } \mathrm { ft }$
C) $30 \sqrt { 10 } \mathrm { ft }$
D) $60 \sqrt { 2 } \mathrm { ft }$