How can I align this perfectly?


in this drawing you’re seeing the top left corner of a trapezoid that is placed inside a box.
Bildschirmfoto 2021-05-28 um 12.13.41
I would like to align the upper line of the trapezoid with the above horizontal line. In oder to do this I click on the white circle that appears when hovering the mouse over it,
then select the arrow that is pointing upwards and finally insert a value. I do succeed to align these two lines however, when I do that the entire trapezoid is moving upwards so that the bottom line disconnects from where I want it to be. (Please see screenshot in next post)

Bildschirmfoto 2021-05-28 um 12.17.04

Bildschirmfoto 2021-05-28 um 12.22.03
So my questions is, what do I need to do to avoid the entire trapezoid from moving upwards? How can I align both the top and the bottom line of the trapezoid to the adjacent lines?

Thanks in advance for your help, Zumen