Question

A ladder rests against a tree. If it reaches a height of 40 m from the ground, and if the distance between the foot of the ladder and the tree is 30 m, then the length of the ladder is ___ m.

• A. 25
• B. 45
• C. 50
• D. 100

Answer 1

The correct option is C

50

Using Pythagoras theorem we have, $c^2=a^2+b^2$

$c^2={30}^2+{40}^2$

$c^2=900+1600$

$c^2=2500$

$c^2={50}^2$

$c=50m$

Hence (C)

Aid to memory-

3-4-5 Pythagoras Triplet