In trigonometry generally, we use the right angle triangle
why ??
It is because you are standing on a road facing the opposite side of a building.
Mark the points
* standing place
* building bottom
*building top
Now connect the three points you will get a right angle triangle
yes...!!! It's evident for this triangle we are using trigonometry
*Adjacent: which is nothing but baseline here the baseline is your point and building bottom
* opposite: which is opposite to the line of adjacent 90 deg
*Hypotenuse: which is the largest line