What is the Rate of Change of Area for a Heated Circular Plate?

[Jan Hill]

Homework Statement

When a circular plate of metal is heated in an oven, its radius increases at a rate of
0.04 cm/min At what rate is the plate's area increasing when r is 54 cm

Homework Equations

The Attempt at a Solution

let r be the radius

dy/dr = 0.04 cm/min

but where to go from here?

 

[tiny-tim]

Hi Jan!

When a circular plate of metal is heated in an oven, its radius increases at a rate of
0.04 cm/min At what rate is the plate's area increasing when r is 54 cm
…
let r be the radius

dy/dr = 0.04 cm/min

but where to go from here?

(what's y ? )

That isn't dy/dr, it's dr/dt.