What is the shortest distance from the point (2,1) to the line x-y= -1
given a point (a,b) not on the line, the distance from that point to Ax + By + C = 0 is
|aA + bB + C|/(√(A^2+B^2)
so distance
= |2(1) + 1(-1) + 1 |/√(1+1)
= 2/√2 or after rationalizing, = √2