I have a face which has the shape like this:


And I want to get something like this:


How to do it?

You can place the edges via edge loop command and position it accordingly (actually eyeballing). To place them parallel to the outer edge you need to take the vertices on one end and move them in the desired way.
One other option is to extrude the face without elevating it. Here you should get the edges parallel to the outer edge.

you can use the Modelling tool kits - multi cut tool and hold down (shift + ctrl which should let you move 10 percent each time) this is from memory as i am at work atm

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