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Geometry Difficulty 3.1 AMC 10/12 Find the answer

Given the hyperbola CC: x2a2y2b2=1\dfrac{x^{2}}{a^{2}} - \dfrac{y^{2}}{b^{2}} = 1 (a>0,b>0a > 0, b > 0) with an eccentricity of 22, and the distance from the right focus to one of the asymptotes is 3\sqrt{3}, the equation of the hyperbola is:

Pick one

Solution

According to the problem, the hyperbola CC: x2a2y2b2=1\dfrac{x^{2}}{a^{2}} - \dfrac{y^{2}}{b^{2}} = 1 (a>0,b>0a > 0, b > 0) has an eccentricity of 22,
thus e=ca=2e= \dfrac{c}{a}=2, which means c=2ac=2a,
and since the distance from the right focus to one of the asymptotes is 3\sqrt{3}, we have b=3b= \sqrt{3},
also, from c2=a2+b2c^{2}=a^{2}+b^{2}, we get 4a2=a2+34a^{2}=a^{2}+3,
which leads to a2=1a^{2}=1,
therefore, the equation of the hyperbola is: x2y23=1x^{2}- \dfrac{y^{2}}{3}=1;
hence, the correct choice is: B\boxed{B}.
According to the problem, by using the formula for the eccentricity of a hyperbola, we get e=ca=2e= \dfrac{c}{a}=2, which means c=2ac=2a. Also, from the properties of the hyperbola, we find b=3b= \sqrt{3}. Combining this with c2=a2+b2c^{2}=a^{2}+b^{2}, we can calculate the value of a2a^{2}, and substituting the values of a2a^{2} and b2b^{2} into the equation of the hyperbola gives us the answer.
This problem examines the geometric properties of the hyperbola, noting that the distance from the focus to the asymptote of the hyperbola is bb.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.