In the tutorial 10 () after the instruction sector1.triangle = new TRIANGLE[numtriangles]; I would like to know when that dynamic memory is freed?

never ? :)

so can i free that memory in order to avoid a memory leak?

so can i free that memory in order to avoid a memory leak? I have tried to free it before the return statement of the SetUpWorld function but it doesn't work any more

You can't free the memory at the end of SetUpWorld because you still need the data elsewhere.
try to free the memory at the end of winMain.

thanks for advice