Solve A=piR(r+2h)

$$A = \pi R ( r + 2 h )$$

Solve for R

$$\left\{\begin{matrix}R=\frac{A}{\pi \left(r+2h\right)}\text{, }&r\neq -2h\\R\in \mathrm{R}\text{, }&A=0\text{ and }r=-2h\end{matrix}\right.$$

Steps for Solving Linear Equation

Use the distributive property to multiply \pi R by r+2h.

$$A=\pi Rr+2\pi Rh$$

Swap sides so that all variable terms are on the left hand side.

$$\pi Rr+2\pi Rh=A$$

Combine all terms containing R.

$$\left(\pi r+2\pi h\right)R=A$$

Divide both sides by \pi r+2\pi h.

$$\frac{\left(\pi r+2\pi h\right)R}{\pi r+2\pi h}=\frac{A}{\pi r+2\pi h}$$

Dividing by \pi r+2\pi h undoes the multiplication by \pi r+2\pi h.

$$R=\frac{A}{\pi r+2\pi h}$$

Divide A by \pi r+2\pi h.

$$R=\frac{A}{\pi \left(r+2h\right)}$$

Solve for A

$$A=\pi R\left(r+2h\right)$$