# A fence(3m tall) parallel to the wall of a building and 1m from the building.What is the length of the shortest ladder that can be extend from the ground over the fence to the building wall?

##### 1 Answer

Sep 16, 2015

the minimum length of ladder is 5.406m

#### Explanation:

answer is very simple . the length of the ladder which is to be caluclated must be minimum .

so the length of the ladder = 3*cosec (x)+sec(x)

applying derrivation on both sides gives the minimum length of ladder required

0= -3cosec(x)cot(x)+sec(x)tan(x)

that implies

x=55.7 degrees

the minimumlength of the ladder is 3cosec(55.7)+sec(55.7) (in degrees)

the minimum length of the ladder is 5.406m