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  1. The height of a tower is 100 m. When the angle of elevation of the sun changes from 30° to 45°, the shadow of the tower becomes P meter smaller. The value of P is :
    1. 100 m
    2. 100 √3 m
    3. 100( √3 - 1) m
    4. 100 m
      3
Correct Option: C

As per given figure , we have
Let, AB be the tower and AC and AD be its shadows.
Then, AB = 100 m.
In triangle BDA ,

AD = cot45° = 1 AD = 1
AB100

⇒ AD = 100 m.
And In triangle BCA ,
AC = cot30° = √3 AC = √3
AB100

⇒ AC = 100 √3 m.
P = AC - AD = 100(√3 - 1) m.
Hence ,The value of P is 100(√3 - 1) m.



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