Question

Find the direction consises of 5i+2j+4k

Answer 1

u = 5i + 2j + 4k

|u|cos a = 5

cos a = 5/ root(5^2 +2^2 +4^2)

cos a = 5/root 45 = root 5/ 3

a = cos^-1(root 5/ 3) -----1

Similarly find others...

|u|cos b = 2

cos b = 2/ root(5^2 +2^2 +4^2)

cos b = 2/root 45

b = cos^-1(2 / root 45) -------2


|u|cos c = 4

cos c = 4/ root(5^2 +2^2 +4^2)

cos c = 4/root 45

c = cos^-1(4/ root 45)


Thanks