In regards to shooting at Monsters like the Mumak, how exactly does in the way work in regards to terrain that is located between the shooter and and the monster?

Imagine a scenario where a ranger is shooting a bow at a mumak that is 18" away and there is a lone pine tree (~2" wide) located at 9" between him and the monster. Would you make an in the way test for the tree? That is, technically there is an obstruction between the shooter and the target. But considering the size of the mumak, large parts of the model (areas larger than the size of a human model) are clearly visible and not blocked by the tree.

Apologies in advance if I am not using all of the right rules terminology - I just remembered this issue while at my office and don't have my copy of the rules handy.

Thanks!

If the Mumak is partially hidden behind a tree then you make in the way test.