hi my name is ken. i am a 11th grader taking calculus for my first year. Here are 3 problems my teacher is giving us in preparation for the upcoming test... I'm pretty clueless ! hope you guys could clear up the confusion for me. The pic: 1. So altitude is the height. What i get from this is that the height is increasing by 2 cm/min and the area is increasing by 4.5 cm/min. the question asks for what the rate of change is for the base when the height is 10.5cm and the area is 100cm. Do I start off by taking the differentiation? 2. Area of circle = pi*r^2 differentiate. dA/dt = 2pi*r * dr/dt dA/dt= 2pi(5) * 5 dA/dt= 50pi/sec 3. I am really confused about this one too. the equation is y= 3 sqrt(4x+4) and the poitn passes through (3,12). I tried graphing this and plotting the point and also graphing the line since its 3 units per second but i have no idea where to start this using calculus. my teacher does not allow us to use the calculator on tests. Thank you.