Resultant velocity is calculated using which two math functions?

Sine and cosine

Explanation:

Velocity is a vector, so it can be resolved into two components into two perpendicular direction.

Generally, we take the x- and the y- direction of the cartesian plane.

If call v the velocity vector, then the components of the velocity along the two directions are:

where is the angle between the direction of the velocity and the x-axis.

Therefore, the resultant velocity can be found from its components by re-arranging the two equations above:

Therefore, the two functions that are used are the sine and the cosine.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.