4- , , .
CV. . , .
, . , , .
, 4 () :
x y
P1 -2 -5
P2 1 7
P3 4 5
P4 3 -2
P1, . :

. k 0: d.
k - Y , X.
d , d. ,
k=dy/dx
d=y1-k*x1
.
k_inv = 1/k
d_inv = -d/k
k d k d
p1p2 4 3 p1p2_inv 0.25 -0.75
p2p3 -0.67 7.67 p2p3_inv -1.5 11.5
p3p4 7 -23 p3p4_inv 0.14 3.29
p4p1 0.6 -3.8 p4p1_inv 1.67 6.33
, DIV/0 , .
, , k . P2 P3.
P2 y P2 P1 P3 .
a=p2p3_inv(y)-p1p2_inv(y)
x x = p2p3_inv (y) x = p1p2_inv (y) y y .
b_candidate_1 = y-p4p1(p2p3_inv(y))
b_candidate_2 = y-p4p1(p1p2_inv(y))
b_candidate_3 = y-P3p4(p2p3_inv(y))
b_candidate_4 = y-P3p4(p1p2_inv(y))
b.
, , a * b.
excel, :

b 6,9, p2p3, b .
,
Rect x y
R1 0.65 -1.3
R2 0.65 5.6
R3 3.1 5.6
R4 3.1 -1.3

++ , , "".
, a b = a * b , , p1p2 P1 P2 ....