Calculating Coefficient of Lift: Angle of Attack of 7°

[yecko]

1. Homework Statement
https://i.imgur.com/tG9unNs.png

2. Homework Equations
in picture below

3. The Attempt at a Solution
https://i.imgur.com/egZC3Ay.jpg

I calculated the angle of attack is "7", yet the answer is "1", which implies the coefficient of lift is about 0.2 from the answer. I am not sure where of my answer have got mistake...
can anyone help?
thank you very much!

 

[FactChecker]

I think there is a problem of slugs versus lbs. Standard atmosphere has density 0.000889378 slugs/cubic foot, not lbs/cubic foot. Using your numbers, I get C_l = 7.3, which is way too high. But dividing by 32.2 gives C_l = 0.23

 

[yecko]

Thank you very much!

Standard atmosphere has density 0.000889378 slugs/cubic foot, not lbs/cubic foot.

It is because https://i.imgur.com/a43giFt.png is what I have got in my assignment and I misunderstood lb(f) as lb(m) represented by lb in the question.

So, I do not need to multiply 32.2 on the right side.

But dividing by 32.2 gives Cl = 0.23

Thank you so much for reminding me!