On a sunny day, the length of the shadow on the ground from the 1.8 m high Christmas tree is 90 cm

On a sunny day, the length of the shadow on the ground from the 1.8 m high Christmas tree is 90 cm, and from the birch 10 m. What is the height of the birch?

To find out the height of the birch, we use the ratio: He / Le = Hb / Lb, from where we express: Hb = He * Lb / Le.

Data: He – tree height (He = 1.8 m); Lb – birch shadow length (Lb = 10 m); Le – the length of the tree shadow (Le = 90 cm, in the SI system Le = 0.9 m).

Let’s make a calculation: Hb = He * Lb / Le = 1.8 * 10 / 0.9 = 20 m.

Answer: d) The height of the birch is 20 meters.