Answer:
45 feet
Step-by-step explanation:
Set up a proportion using the following setup:
height/shadow=height/shadow
The flagpole has a height of 20 feet and casts and 8 foot shadow.
20 feet/8 feet= height/shadow
The goalpost has a height of x (unknown) feet and a shadow of 18 feet.
20 feet/8 feet= x feet / 18 feet
20/8=x/18
x is being divided by 18. The inverse of division is multiplication. Multiply both sides by 18.
18*(20/8)=(x/18)*18
18*20/8=x
18*2.5=x
45=x
x= 45 feet
The goal post is 45 feet tall.
