1. The problem statement, all variables and given/known data An Isosceles triangle has two equal sides of length 10cm. Let x be the angle between the two equal sides. a. Express the area A of the triangle as a function of x in radians. b. Suppose that x is increasing at the rate of 10 degrees per minute. How fast is A changing at the instant x = pi/3? At what value of x will the triangle have a maximum area? 2. Relevant equations 3. The attempt at a solution For part A, I know the answer is 50sin(x) using the double angle formula for B) dx/dt=10degrees=0.1745rad da/dt=50cos(x)(dx/dt) =50cos(pi/3)(0.1745) =4.36cm^2/min For max area, using optimization techniques: A'=50cosx >0 for 0<x<pi/2 and 3pi/2<x<2pi (since dimensions can't be negative) A' <0 for pi/2<x<3pi/2 A'= 0 for x= pi/2 and 3pi/2 Using closed interval method: A(pi/2)=50 A(3pi/2)=-50, therefore A will be max when x=pi/2 I put this in another thread from about a year ago but the information was scrambled and I didn't receive any feedback, anyone mind taking a look at this to see if it's correct?