Question

The angle between I+j and j+k

Answer 1

Answer:

Let the angle between (i+j) and (j+k) be "$\alpha$"

Now ,

cos$\alpha$ = (i+j).(j+k)/|(i+j)|.|(j+k)|

Now,

|(i+j)| = (1^2 + 1^2 )^1/2

= 2^1/2

and,

|(j+k)| = (1^2 + 1^2 )^1/2

= 2^1/2

Therefore,

cos$\alpha$ = 1/(2^1/2×2^1/2)

= 1/2

cos$\alpha$ = cos60(degree)

$\alpha$ = 60degree.

hope it helps you