Solve 20^2=AD^2+12^2

$$20 ^ { 2 } = A D ^ { 2 } + 12 ^ { 2 }$$

Solve for A

$$A=\frac{256}{D^{2}}$$

$$D\neq 0$$

Steps for Solving Linear Equation

Calculate 20 to the power of 2 and get 400.

$$400=AD^{2}+12^{2}$$

Calculate 12 to the power of 2 and get 144.

$$400=AD^{2}+144$$

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

$$AD^{2}+144=400$$

Subtract 144 from both sides.

$$AD^{2}=400-144$$

Subtract 144 from 400 to get 256.

$$AD^{2}=256$$

The equation is in standard form.

$$D^{2}A=256$$

Divide both sides by D^{2}.

$$\frac{D^{2}A}{D^{2}}=\frac{256}{D^{2}}$$

Dividing by D^{2} undoes the multiplication by D^{2}.

$$A=\frac{256}{D^{2}}$$

Solve for D

$$D=\frac{16}{\sqrt{A}}$$

$$D=-\frac{16}{\sqrt{A}}\text{, }A>0$$