Bantu jawab nomor 4 dong dan sertakan cara kerjanya ya

BA = a – b = (2,3) – (-1, -1) = (3, 4)
BC = c – b = (5, -1) – (-1, -1) = (6, 0) => |BC| = √(6^2 + 0^2) = √36 = 6
BA.BC = 3(6) + 4(0) = 18
a) BD = {(BA.BC)/|BC|^2} . BC
= 18/6^2 BC
= 1/2 (6, 0)
= (3, 0)

b) BD = d – b => d = BD + b = (3,0) + (-1, -1) = (2, -1)
Jadi D = (2, -1)