ans
018216
$(1,0)$

018217
$\dfrac{1}{6}$

018218
$4\pi$

018219
$45^\circ$

018220
$y=\sqrt{2} x$和$y=-\sqrt{2}x$

018221
$(x-1)^2+(y-1)^2=5$

018222
$0.10$

018223
假

018224
$\dfrac{\pi}{3}$

018225
\textcircled{1}\textcircled{2}\textcircled{4}

018226
$\dfrac{\pi}{4}$或$\arccos\dfrac{3\sqrt{34}}{34}$

018227
$4900$

018228
C

018229
D

018230
A

018231
B

018232
(1) $-2$; (2) $11$

018233
(1) $\dfrac{2\sqrt{5}}{5}$; (2) $4x-3y-3=0$或$y+1=0$

018234
(1) $x=0.005$, $y=0.045$, 中位数为$26.5$(分), 众数为$25$(分), 极差为$36$(分); (2) 估计中位数为$26$分, 平均数为$29.1$分, 方差为$82.39$

018235
(1) 证明略; (2) $\dfrac{5\sqrt{21}}{21}$; (3) $MC=-1+\sqrt{5}$;

018236
(1) $\dfrac{\sqrt{2}}{2}$; (2) 过定点$P(-1+\sqrt{2},-\dfrac{\sqrt{2}}2-1)$; (3) 直线$PQ$与圆相切