The situation of the Plane, its Altitude and the location of the control tower and the factory has been depicted in the figure above. The angles of depression as observed from the Plane will be same as the angle of elevation of the plane as observed from the two locations, as shown.The Distance CF is 4.8 miles.

Consider Rt Triangles PBC and PBF,

BC= h Cot 13.1 and BF= h Cot 4.1,

Hence CF= 4.8= hCot4.1 – hCot13.1, giving h= =

= miles

=.4959 miles

= .4959(1760)(3)= 2618.69 ft

Rounded off to the nearest 10 ft, h= 2620 ft

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