Extracted text: II. Solve the following problems. Show details and illustrations. 1.The sides of an equilateral triangle are increasing at the rate of 3 cm/min. a) the rate of change of the perimeter. b) the rate of change of the area when the side is 3 cm. long. Find: 2. An open rectangular box w/ square ends to hold 6400 cu ft, is to be built at a cost of Php 75.00 per sq ft. for the base and Php 25.00 /sq ft for the sides. Find the most economical dimensions. 3. A rectangle is inscribed in a right triangle of sides 5, 12, and 13. What are the dimensions of the rectangle of greatest area if the its sides coincides with the legs of the triangle.