Vector?????

for what value of a are the vectors 60i + 3j,40i - 8j,ai - 52j collinear??|||the position vectors of the points are given i think.


let the pts be A,B,C


then vector AB = (40i - 8j)-(60i + 3j) = -20i -11j


and vector BC = (ai - 52j)-(40i - 8j) = (a -40)i - 44j





as they are collinear,


(a-40)i - 44j = m(-20i -11j)


then,


a-40 = -20m


and -44 = -11m


or m =4


so a-40 = -80


or,a = -40





ans : a = -40