'计算夹角函数 OaJB=J%
Function ff_angle(x1 As Single, y1 As Single, x2 As Single, y2 As Single, x3 As Single, y3 As Single) As Single 0nn okN^
cax = x2 - x1 WARb"8Kg
cay = y2 - y1 +a&p$\
cbx = x2 - x3 hT$~ygQ
cby = y2 - y3 M` q?Fk
mo_jj = cax * cbx + cay * cby f.aSKQD
mo_ca = Sqr(cax * cax + cay * cay) !TZhQiorC
mo_cb = Sqr(cbx * cbx + cby * cby) N8qDdr9p?c
cos_acb = mo_jj / (mo_ca * mo_cb) Wcb7
;~K
'ff_cos = cos_acb 7^wc)E^H
If cos_acb >= 1 Then *D o/+[Ae
nn = 0 .)}@J5P)
ElseIf cos_acb <= -1 Then swA+f
nn = 3.14159265258979 `U+l?S^$
Else 8^Hn"v
nn = Atn(-cos_acb / Sqr(-cos_acb * cos_acb + 1)) + 2 * Atn(1) ju}fL<