ABC is isosceles triangle, right angled at A. The resultant of the forces acting along `vec(AB), vec(AC)` with magnitudes `1/(AB)` and `1/(AC)` respectively is the force along `vec(AD)`, where D is the foot of the perpendicular from A on BC. The magnitude of the resultant is:

Options

A. `((AB)(AC))/(AB + AC)`
B. `1/(AB) + 1/(AC)`
C. `1/(AD)`
D. `(AB^(2) + AC^(2))/((AB)^(2)(AC)^(2))`

Answer

C