How do you find the height of a 3d object such as a triangle or a cylinder

Well, for ANY prism (included cylinder), divide volume by area of base.

h = V / B

For ANY pyramid (included cone), divide volume by area of base, then multiply it by 3.

h = 3V / B

In the case of a cylinder, one or several of the following data must be provided: the total area/lateral area and the circumference/area of the base or the area of the base and the volume. Ex: provided the circumference of the base = 10π inches, and the lateral area = 50π inches², the equation can be written as 50π : 10π = 5 inches.