Question

How did they get 21.6?

Answer 1

Answer:

Below.

Step-by-step explanation:

There are 2 similar triangles here.

The large one made from the tree, the trees's shadow  and the line from top of the tree to the and of the shadow The other one is the small triangle inside the large one , made from emily , emily's shadow  and line from top of emily's head to the end of the shadow.

Corresponding sides in these 2 triangles  are in the same ratio, so if  h is the height of the tree, then

h / emil's height = length of tree's shadow / length of emily's shadow

h / 6 = 18/5

5h = 6*18

5h = 108

h = 108/5

= 21.6.

The scale factor for emily's to the object  = 5/18.