Cut an equilateral triangle (one side of the triangle is the width of the rectangle) from a rectangular iron plate with a circumference of 14 cm. Set the width as X and the area of the remaining meter as y CM & su 1. Establish the function analytic expression of Y and X? 2. When it is, the remaining area is the largest? Help!

Cut an equilateral triangle (one side of the triangle is the width of the rectangle) from a rectangular iron plate with a circumference of 14 cm. Set the width as X and the area of the remaining meter as y CM & su 1. Establish the function analytic expression of Y and X? 2. When it is, the remaining area is the largest? Help!


Y = (14 / 2-x) * x-x ^ 2 * radical 3 / 4
You can get the maximum area by making the vertex form