Working With Projections.

Here are some ways to work with projections in ArcMap:

• Define a projection : To define a projection for a CAD dataset, you can:
  1. Open the Arc Toolbox pane 
  2. Click Data Management Tools > Projections and Transformations > Define Projection 
  3. Select the CAD dataset in the Input Dataset or Feature Class section 
  4. Click the browse icon in the Coordinate System section 
  5. Select the coordinate system for the CAD dataset in the Spatial Reference window 
  6. Click OK in the Define Projection window 
  7. Rename the projection file with the same name as the CAD dataset, but with the extension .prj 
• Change the projection of a dataframe: To change the projection of a dataframe, you can:
  1. Right-click in the map and select Properties > Coordinate System 
  2. Select the Coordinate System tab 
  3. Choose a coordinate system from the tree or import one from a data source 
  4. Click OK 
• Create a custom projected coordinate system :To create a custom projected coordinate system, you can:
  1. Double-click Border in the Contents pane to open the Map Properties window 
  2. Click the Add Coordinate System button on the Coordinate Systems tab 
  3. Choose New suggested projected coordinate system 
  4. Type a name for the coordinate system 
  5. Set the geographic coordinate system 
  6. Click Map Neatline under Get extent from 
  7. Choose a projection property