Problem 4 of 34geo-004
On a sunny afternoon, a vertical fence post feet tall casts a shadow feet long on level ground. At the same moment, a nearby tree casts a shadow feet long. How tall, in feet, is the tree?
Try it first
The walkthrough opens once you check an answer.
Solution walkthrough1:49
- The sun hits the post and the tree at the same angle, so their two right triangles are similar.
- Similar triangles keep matching sides in the same ratio. Height over shadow is equal for both.
- Tree: height , shadow . Post: height , shadow . So .
- Multiply both sides by : feet.
- Traps: flips one ratio. and add ( and ) instead of scaling.