Work done against gravity to climb upwards is always stored in the form of gravitational potential energy
so we can say
[tex]W = mgh[/tex]
here h = vertical height raised
so here we know that
[tex]h = 14.1 sin7.3 km[/tex]
here we have
[tex]h = 1.79 km[/tex]
now from above equation
[tex]W = (83 kg)(9.81 m/s^2)(1.79 \times 10^3 m)[/tex]
[tex]W = 1.46 \times 10^6 J[/tex]
so work done will be given by above value