i want it to be like this
but when i click the minus front, both objects got cut out like this;
so how? how do you combine it like in the first picture?
here the 2 original objects before i click minus front;
If you hold down Shift, you can delete the sections of lines that are between intersections of selected Items.
I post an answer instead of comment because I use pictures.
If I had the picture as you and needed to create the picture you need I'd do the follows:
Select the upper shape and click
Object->Path->Divide Objects Below
I've got this picture -
After I join the two selected triangles in pathfinder by pressing Join button and this is the final image -
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