Solve the Problem $y^{2}-x^{2}=21$ , Where $x$ And $y$ Are in Meters $\mathrm{w}$ , Between the Two Outside Walls

Multiple Choice

Solve the problem. Round your answer to the nearest tenth.
-The roof of a building is in the shape of the top half of the hyperbola $y^{2}-x^{2}=21$ , where $x$ and $y$ are in meters. Refer to the figure and determine the distance, $\mathrm{w}$ , between the two outside walls.

A) $8.4 \mathrm{~m}$
B) $5.3 \mathrm{~m}$
C) $28.0 \mathrm{~m}$
D) $10.6 \mathrm{~m}$