AP EAPCET 24-Aug-2021 Shift 1 Paper

Given,

→

A

=2

^

i

+4

^

j

+4

^

k

and

→

B

=4

^

i

+2

^

j

−4

^

k

.
Let θ be the angle between A and B.
By using dot product,
A.B=AB‌cos‌θ,
where, A and B are magnitudes of A and B respectively.
Now, A=√22+42+42=6
B=√42+22+(−4)2=6
Substituting the values, in dot product, we get
(2

^

i

+4

^

j

+4

^

k

).(4

^

i

+2

^

j

−4

^

k

)=(6) (6) cos‌θ
8+8−16=36‌cos‌θ
cosθ = 0
⇒ θ = 90°