gaokao 2017 Q9

gaokao · China · national-II-science Conic sections Eccentricity or Asymptote Computation
9. If the hyperbola $C : \frac { x ^ { 2 } } { a ^ { 2 } } - \frac { y ^ { 2 } } { b ^ { 2 } } = 1 ( a > 0 , b > 0 )$ has an asymptote that cuts the circle $( x - 2 ) ^ { 2 } + y ^ { 2 } = 4$ with a chord of length 2, then the eccentricity of $C$ is
A. $2$
B. $\sqrt { 3 }$
C. $\frac { 2 \sqrt { 3 } } { 3 }$
D. $\frac { \sqrt { 5 } } { 2 }$
9. If the hyperbola $C : \frac { x ^ { 2 } } { a ^ { 2 } } - \frac { y ^ { 2 } } { b ^ { 2 } } = 1 ( a > 0 , b > 0 )$ has an asymptote that cuts the circle $( x - 2 ) ^ { 2 } + y ^ { 2 } = 4$ with a chord of length 2, then the eccentricity of $C$ is\\
A. $2$\\
B. $\sqrt { 3 }$\\
C. $\frac { 2 \sqrt { 3 } } { 3 }$\\
D. $\frac { \sqrt { 5 } } { 2 }$