Does anyone know what the answer is?

the part of the wave he is travelling on is the crest

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

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach