# Question #24864

##### 1 Answer

Jun 22, 2017

#### Explanation:

#"we can assume a right angle between the ground and"#

#"the building"#

#"using "color(blue)"Pythagoras' theorem"#

#("ladder")^2=3^2+4^2#

#color(white)(xxxxxx)=9+16=25#

#color(blue)"take the square root of both sides"#

#rArr"ladder " =sqrt25=5" feet"#

#"the result is a well known "color(blue)"Pythagorean triple"#

#"that is a " 3,4,5" triangle"#

#"others include"#

#5,12,13" and " 7,24,25#

#"these are worth knowing as they occur frequently"#

#"Pythagorean triples can be formed using"#

#n,(n^2-1)/2,(n^2+1)/2" for " n>=3#

#"for " n=9to9,40,41#