Aladder, 100m long reaches a point on the high-rise building that is 80m
above the ground. if the ground is horizontal, how many meters from the foot
of the building is the foot of the ladder?

The distance between the foot of building to foot of ladder is 60 meters

Solution:

Given that A ladder, 100 m long reaches a point on the high-rise building that is 80 m  above the ground

Given that ground is horizontal

The ladder, building and ground forms a right angled triangle

The figure is attached below

In the right angled triangle ABC,

AC represents the length of ladder

AC = 100 m

AB represents the height of building

AB = 80 m

BC represents the distance between the foot of building to foot of ladder

BC = ?

Pythagorean theorem, states that the square of the length of the hypotenuse is equal to the sum of squares of the lengths of other two sides of the right-angled triangle.

By above definition for right angled triangle ABC,

Taking square root on both sides,

Thus the distance between the foot of building to foot of ladder is 60 meters