IO. The sides of a triangle are in arithmetical progression, the square of the middle side exceeds the product of the other two sides by 529, and the area is 1116; find the sides. Ans. 39, 62, 85.

II. If the sides of a right-angled triangle are in arithmetical progression, shew that they are proportional to the numbers 3, 4, 5.

12. Find the sides of a rectangle inscribed in a triangle whose sides are 13, 37, 40, having one side parallel to the greatest side of the triangle, and the ratio of the sides as Io to I. Ans. 30, 3.