Which for small angles cos ⁡ ( α ) = 1 {\displaystyle \cos(\alpha )=1} and sin ⁡ ( α ) = α {\displaystyle \sin(\alpha )=\alpha } , β = 0 {\displaystyle \beta =0} , C z = C L − C d ∗ α {\displaystyle C_{z}=C_{L}-C_{d}*\alpha } , C z = C L {\displaystyle C_{z}=C_{L}} simplifies to: