Answer: 23.09 m
Explanation:
Hi, since the situation forms a right triangle (see attachment) we have to apply the next trigonometric function.
Tan α = opposite side / adjacent side
Where α is the angle of elevation that the dog is looking up, the opposite side (x) is the height of the tree house, and the adjacent side is the distance between the dog and the tree house base.
Replacing with the values given:
Tan 30 = x/ 40
Solving for x
tan30 (40) =x
x= 23.09 m
Feel free to ask for more if needed or if you did not understand something.