Answer:
140 cm
Explanation:
The distance of the foot of the ladder from the building can be found using the Pythagorean theorem (or your knowledge of Pythagorean triples). Once the two distances are found, their difference can be found.
Position 1
The 650 cm ladder reaches 520 cm up the side of the building. The ratio of these side lengths is 650/520 = 5/4, suggesting these are the sides of a 3-4-5 right triangle. The distance from the building is ...
(3/5)×650 cm = 390 cm.
Alternatively, the distance (a) from the building can be found using the Pythagorean relation ...
a² +b² = c²
a² +520² = 650²
a = √(422500 -270400) = √152100 = 390 . . . cm
Position 2
The 650 cm ladder reaches 520 +80 = 600 cm up the side of the building. The ratio of these side lengths is 650/600 = 13/12, suggesting these are the sides of a 5-12-13 right triangle. The distance from the building is ...
(5/13)×650 cm = 250 cm
Again, the Pythagorean theorem can be used to obtain the same result:
a = √(422500 -360000) = √62500 = 250 . . . cm
Difference
The difference between the two distances is ...
390 cm -250 cm = 140 cm
The foot of the ladder will be 140 cm closer to the building.