foam
Water, foam, powdered chemicals like sodium bicarbonate
"Courageous firefighter" isn't a word.
Water
the brim is designed todivert water to back and to prevent water from going down the firefighter back.
A firefighter extinguishes fire to keep people safe.
Firefighters use water, predominantly, to fight forest fires. Sometimes they can sprinkle a compound to reduce the spread of flames, but water is the typical method.
a basic firefighter does not use any math but if you are an EO (Engine operator) yes you with use math because you have to do pump operations and hydraulics.
Fire Sciences
a firefighter
The plural of fireman is firemen. If you want to use inclusive language, then you can say firefighter and firefighters.
From a fire hydrant
Do to the fact that Firefighters frequently use water, their helmets must be water proof to 1. prevent from adding more weight, and 2. prevent distraction from excess saturation.