Refer to figure.
Steady Descent

Weight is split into 2 components:

• W cos y acts perpendicular to the flight path and balances lift;
• W sin y acts forward along the flight path, adding to Thrust to balance drag.

Lift is less than Weight: Lift only has to balance the component of weight which acts perpendicular to the flight path (L = W cos y).

Thrust is less than drag: Weight gives a forward component in the same direction as thrust.

For a power-on descent, we get the following formulas:

D = T + W sin y
T = D – W sin y
L = W cos y

With regards to this question,

• L = W cos y
• L = 104 500 N x cos 30 = 90 500 N