This question is testing your knowledge of maths.

 

From the notes

 

(Thrust (T) - Drag (D))/ Weight (W) = Sin Gamma

 

Mathematically this could be written

T/W – D/W = Sin Gamma

 

Practical example

(8 – 4) / 2= 2

 

Same as

8/2 – 4/2 = 2

 

Since at small angles of climb lift (L) and weight (W) are considered almost equal you could replace weight with lift, so returning to the mathematical variation of our formula we now get

 

T/W –D/L

 

The next step is to consider lift and drag as coefficients.

 

T/W – CD/CL = Sin Gamma