【简答题】(选做题) 如图所示,圆O的直径AB=6,C为圆周上一点,BC=3。过C作圆的切线l,过A作l的垂线AD,AD分别与直线l、圆交于点D、E,则∠DAC=( ),线段AE的长为( )。
【简答题】已知直线l过点P(0,2),斜率为k,圆Q:x 2 +y 2 -12x+32=0. (1)若直线l和圆相切,求直线l的方程; (2)若直线l和圆交于A、B两个不同的点,问是否存在常数k,使得 OA + OB 与 PQ 共线?若存在,求出k的值;若不存在,请说明理由.
【简答题】已知直线l过点P(-1,2),且倾斜角为 ,圆方程为ρ=2cos(θ+ )。 (1)求直线l的参数方程; (2)设直线l与圆交与M、N两点,求 的值。
【简答题】已知圆C:x 2 +(y-1) 2 =5,直线l:mx-y+1-m=0,m∈R. (1)若直线l过圆C的圆心,求m的值; (2)若直线l与圆C交于A,B两点,且 |AB|= 17 ,求直线l的倾斜角.
【单选题】What problem has the man had in taking pictures?
A.
He can't find good subjects to photogragh.
B.
His indoor shots are too dark.
C.
His pictures are often blurry.
D.
His camera is too big for good detail.
【简答题】已知圆O:x 2 +y 2 =2,直线l:y=kx-2。 (1)若直线l与圆O相切,求k的值; (2)若直线l与圆O交于不同的两点A,B,当∠AOB为锐角时,求k的取值范围; (3)若 ,P是直线l上的动点,过P作圆O的两条切线PC,PD,切点为C,D,探究:直线CD是否过定点。
【单选题】Taking pictures very interesting.
【简答题】When did he start taking pictures?
【单选题】We enjoy taking pictures while .
【单选题】Why does Mark like taking pictures?
A.
Because he can use the photos to get prizes.
B.
Because the photos carry with many sweet memories.
C.
Because taking photos by himself can save money.