Answer: D) 10
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Step-by-step explanation:
y = 5 because the long leg is exactly sqrt(3) times that of the short leg.
The short leg is always opposite the 30 degree angle.
The hypotenuse x is twice that of y, so x = 2y = 2*5 = 10
All of these rules only apply to 30-60-90 triangles. You can use trig ratios as an alternative route.