This equation involves no x variable, so I assume you want to solve this for D.
First of all, you can divide both sides by 0.785 to get
![0.785D^2 = 0.54 \iff \dfrac{0.785D^2}{0.785} = \dfrac{0.54}{0.785} \iff D^2 = \dfrac{0.54}{0.785} =](https://tex.z-dn.net/?f=%200.785D%5E2%20%3D%200.54%20%5Ciff%20%5Cdfrac%7B0.785D%5E2%7D%7B0.785%7D%20%3D%20%5Cdfrac%7B0.54%7D%7B0.785%7D%20%5Ciff%20D%5E2%20%3D%20%5Cdfrac%7B0.54%7D%7B0.785%7D%20%3D%20)
Since the right hand side is positive, the equation make sense (otherwise we would be asking a square, i.e. a positive number, to equal a negative number). So, we can extract the square root from both sides:
![D^2 = \dfrac{0.54}{0.785} \iff \sqrt{D^2} = \pm\sqrt{\dfrac{0.54}{0.785}} \iff D = \pm\sqrt{\dfrac{0.54}{0.785}}](https://tex.z-dn.net/?f=%20D%5E2%20%3D%20%5Cdfrac%7B0.54%7D%7B0.785%7D%20%5Ciff%20%5Csqrt%7BD%5E2%7D%20%3D%20%5Cpm%5Csqrt%7B%5Cdfrac%7B0.54%7D%7B0.785%7D%7D%20%5Ciff%20D%20%3D%20%5Cpm%5Csqrt%7B%5Cdfrac%7B0.54%7D%7B0.785%7D%7D)
Answer:
78.5%
Step-by-step explanation:
You take the area of the circle which is pie*r^2
and divide it by the area of the square
7 hours a week. One hour a day