Find the height of the building ("Fig. 17.13 shows a boy sitting on a platform 7.5m high...")

[chijioke]

This is what I did

The height of the building comprises 7.5m + height indicated by white line (w) + height indicated by green line(g).
Now I can obtain height indicated by the green line:
[math]Tan40=\frac{g}{37.5}[/math][math]g=37.5tan40=30.7~m[/math]So height of the building = g+w+7.5m
That is height of the building=[math]30.7m +w+7.5m[/math]The problem now is how can I obtain w?

 

[topsquark]

View attachment 35734View attachment 35735
This is what I did
View attachment 35738
The height of the building comprises 7.5m + height indicated by white line (w) + height indicated by green line(g).
Now I can obtain height indicated by the green line:
[math]Tan40=\frac{g}{37.5}[/math][math]g=37.5tan40=30.7~m[/math]So height of the building = g+w+7.5m
That is height of the building=[math]30.7m +w+7.5m[/math]The problem now is how can I obtain w?

You can't. Problems like these are all over the place and are all written wrong. This one even comes with a diagram!

Take w = 0 m. You have no way to calculate where eye level is.

-Dan

 

[chijioke]

Thank you.