#$1)$ Consider Figure $1$ showing the NACA $23012,$ in which L and D present the lift and drag forces whereas N and A show aerodynamic forces in normal and along to the chord direction, show that aerodynamic forces N and A can be related to the lift abs drag forces via the relations below:

$L=$Ncos$()-$Asin$()$

$D=$Nsin$()+$Acos$()$

#$2)$ Considering Figure $1$ and the relations derived between aerodynamic forces N and A can be related to the lift and drag forces in Question #$1,$

a$)$ show that there are the relations below between the section normal and axial force coefficients $c_n$ and $C_a$ and lift and drag coefficients $C_l$ and $c_d$ as follows:

$c_l=c_{n}cos()-c_{a}sin()$

$c_d=c_{n}sin()+c_{a}cos()$

b$)$ Calculate $c_n$ and $C_a$ from the above relations $($question $2),$ assume that $=8,c_l=1\mathrm{.}0$ and $c_d=0\mathrm{.}0078.$ Answers: $C_n=0\mathrm{.}991$ and $c_a=-0\mathrm{.}131.$