Cross-sectional area of an assembly

[sully]

Is there an easy way to establish the cross-sectional area of an assembly?My method was tosave as a parasolid and then opened as a part file, then create a cut through the section plane,this enabled me to select the cross-sectional area as one surface however associatively is lost. There must better way?
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[csusie]

I dont know what version of Pro you are using but in WF
3 the menu pick is Analysis->Model->Xsection mass
properties