Не говоря български, но може би снимката по-долу ще бъде полезна... Опитайте да копирате и поставите английския текст в преводач.
I think for either cone, r stands for radius, h is the height, and is the slant height.
Then rotating the triangle about the shorter leg with length a = 3 cm, the resulting cone (on the right in the picture) would have r = 4 cm, h = 3 cm, and = 5 cm.
For the other cone, rotating about the longer leg with b = 4 cm generates a cone with r = 3 cm, h = 4 cm, and = 5 cm.