Q36 of 68 Page 9

A person standing on the bank of a river observes that the angle of elevation of the top of a tree standing on the opposite bank is 60°. When he moves 40 m away from the bank, he finds the angle of elevation to be 30°. Find the height of the tree and the width of the river.[ Use = 1.732 ]


From the ∆ADC,





Now, from the ∆ABC,





Put vale of DC from equation(i) and BD = 40 that is given.


So,



= 34.64


Now, put value of AC in equation(i)



Therefore, height of the tree is 34.64 m and width of the river is 20 m.


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