Question

已知圆C=（X-a)平方+(y-2)平方=4(a>0) 及直线L;x-y+3=0,当直线L被C截得旋长为2倍根号2 则a

Answer 1

d=|a-2+3|/√2=|a+1|/√2

4=(a+1)^2/2+2

(a+1)^2=4

a+1=2 or -2

a=1 or a=-3