Answer:
3/4
Step-by-step explanation:
sin = opposite/hypotenuse
one side is 3, hypotenuse side is 5.
using the pythagorean theorem, we know that the third side is 4.
tan = opposite/adjacent
tanθ = 3/4
The aluminum section's area formula solved for h is 
From the complete question, the expression of the area (A) in terms of variables a, b and h is:

Factor out h from the expression on the right-hand side

Divide both sides of the equation by (a - b)

Remove the bracket

Rewrite the above equation as follows:

Hence, the aluminum section's area formula solved for h is 
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You would divide 228/12 = 19 per class.