Hidden dimension

CadCloud got it right. If a dimension is diifuclt to find, I usually do a fully defined sketch. Most of the time you would not need the missing measurements. :D

Here is the model, hasibul shovon...

Nit need to be defined in the original, the point of that type of example model is search an alternative way to get the dimensions. for this case you have the dimension in the center.

you can draw a side sketch in were the origin of the diagonal lines are the point A and B, then make them parallel an give them the 40mm dimension.

Solidtweak actually i am preparing for CSWA that's why i am practicing.