piramidy by a

I don't understand. Is this supposed to be an attempt at being unsolvable?

Yes the main pyramid is a logical attempt but for the other two their are multiple solution.
The first hint could be that here are 3 pyramids in total.

if not...C1R4 is the start of one
this should be sufficient..

Still no.

Arleta, when you create a hanjie, there is a button you can push to test the puzzle before you submit it. Please test your hanjies before you post them. If you can't complete them by the numbers alone (pretending you don't know what the finished puzzle looks like), it is not logical and should not be submitted.

3 dotted triangles. The big one in the middle is obvious. The left one starts on C1R5. The right one starts on C20R6.