i had a go at it. But, i'm a newbe, so i learned a few things, but im not assuming you can use it ;)
First i made a box and a sphere. (For the screenshot i set the box transparant, and the view in 'perspective')

Then did Part -> Split -> Boolean fragments

Then did Part -> Compound -> Explode Compound

And removed/hidden the excess parts:

Next would be to fuse what's left i guess
But that last part, to flatten the tip with a circle which touches the 3 sides... i'm stuck
