You know how Soh Cah Toa applies to right triangles; you can assign the adjacent side = 4 and hypotenuse = 7
CosФ = (adjacent) / (hypotenuse)
Then with the Pythagorean theorem
4² + b² = 7²
16 + b² = 49
b² = 49 - 16
b² = 33
b = √(33)
So "b" is the opposite side.
SinФ = (opposite) / (hypotenuse) = √(33)/7
TanФ = (opposite) / (adjacent) = √(33)/4
For this case we must find an expression to find 40% of 25. So, we make a rule of three:
25 -----------> 100%
x -------------> 40%
Where "x" represents the amount that determines 40% of 25.

40% of 25 is 10. And an expression to find it is:

Answer:

How much does the molding paper cost. Work out the area of the ceiling which is 15 x 20 and multiply it by the price of the molding paper