Question

If Ā= 2î – 2 – Ã and B = î+ſ, then : (a) Find angle between A and B. (b) Find the projection of resultant vector of A and B on x-axis.​

Answer 1

Answer:

Correct option is

A

θ=90

∘

; 3; −2

i

^

+3

j

^

+

k

^

i)

A

.

B

=ABcosθ

or (2

i

^

−2

j

^

−

k

^

).(

i

^

+

j

^

)=ABcosθ

or 2−2=ABcosθ or cosθ=0⇒θ=90

o

ii) Resultant,

R

=

A

+

B

=(2

i

^

−2

j

^

−

k

^

)+(

i

^

+

j

^

)=3

i

^

−

j

^

−

k

^

The projection of resultant on x -axis =

R

.

i

^

=3

iii) Here,

P

+

A

=

j

^

⇒

P

=

j

^

−

A

=

j

^

−(2

i

^

−2

j

^

−

k

^

)=−2

i

^

+3

j

^

+

k

^