True or false the points where the potential is the same in three dimensional space lie on a surface

Yes

Explanation:

The Three-dimensional space is a geometric arrangement where by three values are needed if they are to determine the position of an element. In physics or in mathematics, a sequence of n numbers can be understood as a location in the n-dimensional space or setting.

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

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west