Expression 18: "y" equals negative "m" Subscript, 2 , Baseline left parenthesis, "x" minus "B" Subscript, 1 , Baseline , right parenthesisy=−m2x−B1
18
Expression 19: "y" equals "m" Subscript, 3 , Baseline left parenthesis, "x" minus "D" Subscript, 1 , Baseline , right parenthesis plus "D" Subscript, 2 , Baseliney=m3x−D1+D2
19
Expression 20: negative "m" Subscript, 2 , Baseline left parenthesis, "x" minus "B" Subscript, 1 , Baseline , right parenthesis equals "m" Subscript, 3 , Baseline left parenthesis, "x" minus "D" Subscript, 1 , Baseline , right parenthesis plus "D" Subscript, 2 , Baseline−m2x−B1=m3x−D1+D2