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					 Angle of depression from the top of a lighthouse of two boats are 45° and 30° due east which are 60 m apart. The height of the light house is :
- 
                        - 60 √3
- 30 ( √3 - 1 )
- 30 ( √3 + 1 )
- None of these
 
Correct Option: C
As per given figure , we have 
Let, the boats be at P, Q. So that PQ = 60m. Let, MA be the lighthouse.
Let, h = MA.
| Then, | h | = | tan45° | = 1. | ∴ h = MP | 
| MP | 
| Again, | h | = | tan30° | = | 1 | 
| MP + 60 | √3 | 
| ∴ MP + 60 | = | √3h or, h + 60 = √3h | 
| ∴ ( √3 - 1 )h = 60 | 
| ∴ | h = | 60 | h = | 60 ( √3 + 1 ) | 30 ( √3 + 1 ) m | 
| √3 - 1 | 2 | 
 
					                    					 
	