Click the 
3D Measurement button in the 3D toolbar to measure vertex distance, edges, angles and several more 3D dimensions. This will display a dialog box with three tabs:
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View: specify measurement type: Ruler, Distance, Radius, Angle or Auto.
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Markup: add markup text to specific measured dimensions.
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Tool Settings: set measurement units and snapping.
We provide other tools for measuring 2D objects and pictures.
