Find the total cost of making a triangular sail that has a base dimension of 14 feet and a height of 30 feet if the price for making the sail is $17.50 per square foot. Solution Given that , height = 30 base = 14 , price of making the sail is 17.5 per square foot , so we need to calculate the total surface area so the area of the traiangle is given as 1/2 * base* height = 0.5 * 14* 30 = 210 square foot so total cost is calculated by multiplying the per square foot cost with the total area 210 * 17.5 = $3675.