a) $d(M, \Delta) = \frac{|8 . 2 - 6 . 3 + 7|}{\sqrt{8^{2} + (-6)^{2}}} = \frac{5}{10} = \frac{1}{2}$
b) $d(M, \Delta) = \frac{|4 . 0 + 9 . 1 - 20|}{\sqrt{4^{2} + 9^{2}}} = \frac{11}{\sqrt{97}}$
c) $d(M, \Delta) = \frac{|0 . 1 + 3 . 1 - 5|}{\sqrt{0^{2} + 3^{2}}} = \frac{2}{3}$
d) $d(M, \Delta) = \frac{|1 . 4 + 0 . 9 - 25|}{\sqrt{1^{2} + 0^{2}}} = 21$