Question 22725: I can not solve this shadow problem. I failed a test and do not understand. Can you help?
Neighbor wants to cut a tree down. He is worried it will fall on his garage which is 42' from the tree.He decided to measure the height of the tree by its shadow. The tree's shadow measured 47 feet. He put a yardstick next to the tree and the yardstick cast a shadow of 4'.
Problem: How tall is the tree in feet?
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! this is 2 similar triangles, so it is just simple ratio:
With ratio, i always tell my students to work in 3 stages:
1. write down what you know
2. Find what one is worth
3. Find what the Questions asks for.
I follow this method myself and i get the question correct. So, you decide if you want to learn my method...
1. I know 4foot shadow is from a 3foot (yardstick) stick
--> 4 from 3
2. so 1 from 3/4 (i got this just from dividing both sides by 4.)
3. so 47 from (3/4)*(47) --> i got this from multiplying both sides by 47
--> so 47 from 35.25feet
Height of the tree is 35.25 feet.
jon.
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