Dr Gulshan S. answered 07/06/21
Physics Teaching is my EXPERTISE with assured improvement
Force due to q2 = K q1 q2 /d2 = Vector F1
Force due to q3 = K q1 q3 /d2 = Vector F2
q1 = q2 = q3 = 22*10 -6 C
d = 0.111 m
Total force on q1 = Vector F1 + Vector F2
Angle between F1 and F2 = 60 degree
Resultant Force
F2 = F1 2 + F2 2 + 2F1 * F2 * Cos 60 ........ Eq 1,
Plug in F1 = F2 = 9*109 *22*10-6 * 22*10-6/ ) / (0.11)2 and Cos 60 = 0.5
Get F as answer