If you need to park the car on a road marked like this because it has broken down, are you obliged to place a warning triangle behind it within a distance of 100 m?

Why?

The visible D-7 sign showing a car marks the start of an expressway. If you stop there because of a breakdown, you must place a warning triangle 100 m behind the vehicle, even if it is on the shoulder.

art. 50 ust. 2 pkt 1 lit. b Prawa o ruchu drogowym