$A = \pi r^2$
Terms
| Term | This example | Why |
|---|---|---|
| equation | ✓ | $A = \pi r^2$ is an equation, because it says that two expressions are equal. |
| formula | ✓ | $A = \pi r^2$ is a formula, because it gives the area $A$ in terms of the radius $r$. |
| identity equation | ✗ | The equation $A = \pi r^2$ is not an identity because is not true for every choice of variables $A$ and $r$, such as for $A = 0$ and $r = 1$. |