Dim Aligned measuring in 2d

Hi all. fairly new to rhino so excuse the basic question. I’m struggling to annotate the length of the long edge or hypotenuse of a truncated cone. Dim Aligned when used to measure the distance between mid points on the top and bottom circle only gives me the dimension in 2d, or side b of the triangle, not the hypotenuse. I can measure it using analyse distance but i would like to annotate. Many thanks. Loz

Dimensions are planar objects that must lie in one plane. Probably you will need to create a custom CPlane that is in the plane of the cone hypotenuse and then use DimAligned to place it.

Thanks very much. this is exactly what i needed. I’ve worked out how to make a custom cplane and get the dimension but can’t work out how to return the cplane to default to continue working on the rest of the drawing. Many thanks

set cplane to world. sorted. thanks again!