1. The line $\left\{\begin{array}{l}x=1+2 t, \\ y=2+t,\end{array}\right.$ ( $t$ is a parameter) intersects the circle $x^{2}+y^{2}=9$ to form a chord of length
A. $\frac{12}{5}$
B. $\frac{12}{5} \sqrt{5}$
C. $\frac{9}{5} \sqrt{2}$
D. $\frac{9}{5} \sqrt{10}$
1. B The equation of the line is $\frac{x-1}{2}=y-2$, substitute it into the equation of the circle, and use the chord length formula.