To show the development of the truncated cone, we first need to determine its key dimensions.

To show the development of the truncated cone, we first need to determine its key dimensions. Given from Figure (a): Base diameter of the cone = 60 mm Total height of the original cone = 100 mm Height of the truncated part (frustum) = 70 mm Step 1: Determine the dimensions of the original full cone. Base radius, R = (60)/(2) = 30 mm Height, H = 100 mm Slant height, L: Using the Pythagorean theorem, L = sqrt(H^2 + R^2) L = sqrt(100^2 + 30^2) L = sqrt(10000 + 900) L = sqrt(10900) ≈ 104.40 mm Step 2: Determine the dimensions of the removed top cone. The height of the removed top cone, h = H - 70 = 100 - 70 = 30 mm. Using similar triangles, the radius of the top surface of the frustum (which is the base radius of the removed top cone), r, can be found: (r)/(R) = (h)/(H) r = R × (h)/(H) r = 30 × (30)/(100) r = 30 × 0.3 = 9 mm The slant height of the removed top cone, l: l = sqrt(h^2 + r^2) l = sqrt(30^2 + 9^2) l = sqrt(900 + 81) l = sqrt(981) ≈ 31.32 mm Step 3: Calculate the sector angle for the development. The development of the full cone is a sector of a circle with radius L. The arc length of this sector is equal to the circumference of the base of the cone (2 R). The sector angle (in degrees) is given by: = (R)/(L) × 360^ = (30)/(104.40) × 360^ ≈ 0.287356 × 360^ ≈ 103.45^ Step 4: Construct the development of the truncated cone (frustum). The development of the frustum is a portion of an annulus. 1. Draw