Translations:Basic Part Design Tutorial 017/32/en

Select New Sketch from the toolbar or Part Design menu. Now in sketch edit mode, we do not see the sketched rectangle of the slope. To make it selectable, we switch the combo view to model tab and select the last sketch made (Sketch003) on the sloped plane. Then using the spacebar, make it visible. Next, select the mirror feature above (mirrored001) and again using spacebar, hide it. Then you should see the rectangle inside the 3D View. You may continue to work with the model tab visible, or switch back to tasks tab. Using the External geometry tool, select the upper and lower  horizontal edges of the sloped rectangle.