The foot of the ladder is
10
feet away from the base of the wall.
Explanation:
Here , the wall , top and foot of the ladder and ground makes a
right triangle of which length of ladder h=18 is regarded as
hypotenuse angle with ground is
θ=60°;cos 0= b/h or
cos 60°=b/18or b=18.cos 60=18.1/2
=9 feet
