## Algebra and Trigonometry 10th Edition

$(A~o~r)(x)=\frac{\pi}{4}x^2$ It is the area $A$ of the circular base of the tank as a function of the length $x$ of sides of the square.
$(A~o~r)(x)=A(r(x))=A(\frac{x}{2})=\pi(\frac{x}{2})^2=\frac{\pi}{4}x^2$