CBSE Class 10 Answered

Good to know that your exam went off well.

 Here's the solution to your question.

Assume AB  to be the 8m tall building.with A as its top and B as its bottom.

Let EC be the multistoreyed building with E as its top and C as its bottom.

Mark D on EC such that DC=8 m(so ABCD is a rectangle)

Let BC=AD= x m and ED = h m

According to question,

angle EAD=30(alternate angle of the angle of depression)

and

 angle EBC=45(same reason as above)

In triangle EAD,

tan 30=ED/AD=h/x

So,

x=hcot30..(i)

Next,

 in triangle EBC,

tan45=(h+8)/x

So,

x=h+8..(ii)

Equating the value of x from both equations, we get,

h+8=h cot 30

h+8=h*(1.732)

8=h*(0.732)

h=8/0.732

calculate the final step and you will have the answer of h.

Add 8  to it and you will get the height of the multistoreyed building.