Let, the unit vector in XY plane be a → , then,
a → =cosθ i ^ +sinθ j ^ (1)
Since θ is the angle with the positive direction of x-axis that is made by the unit vector, then θ=30°.
Substitute θ=30° in equation (1).
a → =cos30 i ^ +sin30 j ^ = 3 2 i ^ + 1 2 j ^
Therefore, the unit vector is 3 2 i ^ + 1 2 j ^ .
Write down a unit vector in XY- plane, making an angle of 30∘ in anticlockwise direction with the positive direction of X-axis.
Vector →A of magnitude 4 units is directed along the positive x-axis. Another vector →B of magnitude 3 units lies in the x-y plane and makes an angle 30∘ with the positive x-axis as shown in the figure. Then →A.→B is