20. |(ax+ by + c)/sqrt. a^2 + b^2 | - recall perpendicular distance formula. distance =1 therefore this always has to = 1.
|(12x-5y-1)/sqrt.169|=1
(12x - 5y - 1) / sqrt.169 = 1 or (12x - 5y - 1) / sqrt.169 = -1
12x - 5y - 1 = sqrt 169 or (12x - 5y - 1) = - sqrt 169
12x -5y - 14= 0 , 12x -5y + 12= 0 AS SQRT169 = 13
HOPE THAT HELPS