Diketahui titik A(-2,-1),B(3,-2),dan C(4,5). Tentukan a. Persamaan garis AB b. Persamaan garis AC c. Persamaan garis BC

a) garis AB
( y - y1 ) / ( y2 - y1 ) = ( x - X1 ) / ( x2 - X1 )
( y + 1 ) / ( - 2 + 1 ) = ( x + 2 ) / ( 3 + 2 )
( y + 1 ) / - 1 = ( x + 2 ) / 5
5 ( y + 1 ) = - 1 ( x + 2)
5y + 5 = - x - 2
5y + x = - 2 - 5
5y + x = - 7

b) garis AC
( y - y1 ) / ( y2 - y1 ) = ( x - X1 ) / ( x2 - X1 )
( y + 1 ) / ( 5 + 1 ) = ( x + 2) / ( 4 + 2)
( y + 1 ) / 6 = ( x + 2 ) / 6
6 ( y + 1 ) = 6 ( x + 2)
6y + 6 = 6x + 12
6y - 6x = 12 - 6
6y - 6x = 6
disederhanakan
y - x = 1