a)
(X - [-7, -1]) * [3/5, 4/5] = 0
d = ([0, 0] - [-7, -1]) * [3/5, 4/5] = 5
b)
y = m * (x + 2) + 4 = m·x + 2·m + 4
d = |m·x - y + 2·m + 4| / √(m^2 + 1^2)
d = |m·0 - 0 + 2·m + 4| / √(m^2 + 1^2) = 2 --> m = - 3/4
y = -3/4 * (x + 2) + 4 = 2.5 - 0.75·x
Ansonsten gibt es noch x = -2
c)
(X - [4, -1, 3]) x ([-1, 4, 0] - [4, -1, 3]) = [0, 0, 0]