A woman is trapped in a burning building, 60 feet above the ground. To rescue the woman, a fireman places the bottom of a large ladder 40 feet from the base of the building. How long must the ladder be to reach the trapped woman?

Height of building = 60 feet (where woman is trapped)

distance of bottom of ladder from base of building = 40 feet

This makes a right angled triangle as shown in figure.

here hypotenuse = length of ladder

base = distance of bottom of ladder from base of building = 40 feet

perpendicular = Height of building = 60 feet (where woman is trapped)

So here we can use Pythagoras theorem to find the length of ladder.

Hypotenuse² = base² + perpendicular²

height of ladder = √ (60² + (40) ² = √3600 + 1600 = √5200

height of ladder = 72.1 feet