Explanation:
Let label this using a triangle.
We are sitting 300 ft away from the building.
We can look up to see the top of building at an angle of 60 degrees. So 60 degrees would be near where we standing at. The other angle of the top triangle would be 30 since that the height of building and the ground horizon is perpendicular to each other so they measure 90 degrees. Using triangle interior theorem, the missing angle would be 30.
We use another triangle since we are looking down.
The height of building and where we sitting at is perpendicular. The angle near we at would measure 15 and the missing angle would be 75.
The triangles both combine to form one triangle. They would form a isoceles triangle.
The most bottom angle of the triangles measure 75 while the angle where we are at of both triangle measure 75. so we have a isoceles triangle.
This means that the hypotenuse of the top triangle is equal to the length of the building.
To find the hypotenuse use 30-60-90 rules,
hypotenuse =twice of most shortest side.
So the length of the building is 600.