## Agentjamesbond007 5 years ago [Related Rates] If A is the area of a circle with radius r and the circle expands as time passes, find dA/dt in terms of dr/dt

like the last one $A=\pi r^2$ $\frac{dA}{dt}=\frac{dA}{dr}\frac{dr}{dt}=2\pi r\frac{dr}{dt}$