From point a the angle of elevation to the top of a tall building is 20 degrees. on walking 80 m towards the building the angle of elevation is now 23 degrees. how tall is the building?

i just want to know how to draw the picture that's all.

First, draw a diagram for a building. Then, from the top of the building, draw a slanting line down to the ground level. That angle is 20 degrees. Then draw another line from the top of the angle to the ground. But this time, nearer to the building. That angle would be 23 degrees. The distance at the ground level between the two lines is 80. The diagram would look like this: