Question

Hey can anyone help with this question?

Answer 1

(AB)^2 + (2 m)^2 = (8 m)^2, or

(AB)^2 + 4 m^2 = 64 m^2, or    (AB)^2 = 60 m^2.

Taking the square root of both sides,    (length of AB) = + 2sqrt(15)  (answer)