A rectangle has a constant area of 200 square meters and its length L is increasing at the rate of 4 meters per second
1)Find the width W at the instant the width is decreasing at the rate of .5 meters per second.
2) At what rate is the diagonal D of the rectangle changing at the instant when the width W is 10 meters?
1)So I know that DL/Dt= 4 and Dw/dt= -.5
So the equation is A=LW, the derivative being Da/dt= L(dw/dt)+W(dL/dt)
Would that be 0=L(-.5)+W(4)
What would I do next there?
2)How would I start this one off?