La magnitud de un vector A es 4 y la magnitud de un vector B es 4. L a magnitud del vector suma de estos vectores A y B es 2. Hallar el angulo entre los vectores A y B

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

electric field is a function of 1/r^2

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