The cone can be represented by two similar isosceles triangles, the smaller being the top section of the larger one. Let the height of the smaller triangle be h, then the height of the larger triangle is h+1.8905. The ratio of the two heights is the same as the ratio of the two diameters, represented by the bases of the triangles. So 1.9250/2.2480=h/(h+1.8905). Cross-multiply: 1.9250(h+1.8905)=2.2480h. 1.9250h+3.6392=2.2480h, 0.323h=3.6392, h=3.6392/0.323=11.2669. Let the common vertex angle be A, then according to the geometry of the triangles, (d1)/2h=tan(A/2)=1.9250/(2*11.2669)=0.08543, A/2=4.8828, so A=9.7655 degrees.