From a window 15m

The figure is given below:

From fig;

AB = 15m

So, AB = CD = 15m

In triangle ABC,

∠ ACB = 45°

tan 45° = 1

⇒ AB = CB

So, CB = 15m

Also, CB = AD = 15m

Now, in triangle EAD,

∠ EAD = 30°

ED = 8.66m

So, height of building = ED + DC = 8.66 + 15

= 23.66m