A 3.7 m long laddder is placed against a wall in such a way that the foot of the ladder is 1.2 m away from the wall up to what hight does the ladder reach the wall...I guess it is Pythagoras theorum which will be used here but not sure about it....

The Height of the wall, the length of the ladder and the distance between the foot of the wall and base of the ladder forms a right angle triangle.

So as per the Pythogoras Theorom:

Hypotenuse²= Base²+ Perpendicular²(Where Hypotenuse = Length of the ladder = 3.7 Mtrs, Perpendicular = Height of the wall = ? and Base = the distance between the foot of the wall and base of the ladder = 1.2 Mtrs.)

So Hypotenuse²= Base²+ Perpendicular²

Perpendicular =√Hypotenuse²- Base²

Perpendicular =√3.7²- 1.2²=√13.69 - 1.44 =√15.13 = 3.889 Mtrs.

Ans: 3.889 Mtrs.