Since the scale factor is greater than 1, this dilation will be an enlargement. Therefore, you multiply 7.2 times 8.1 to get 58.32. This question asks for diameter, so multiply 58.32 times 2 to get 116.64 in.
We can think in this situation as a triangle rectangle.
where:
The height of the tree is one cathetus
The shadow of the tree is the other cathetus.
We know that the angle of elevation of the sun is 78°, an angle of elevation is measured from the ground, then the adjacent cathetus to this angle is the shadow of the tree. And the opposite cathetus will be the height of the tree.
