View angle - river

The 15 m high building is 30 m away from the river bank. The river's width can be seen from the roof of this building at an angle of 15°. How wide is the river?

Final Answer:

y =  43.3 m

Step-by-step explanation:

h=15 m x=30 m  α=15° rad=15° 180π =15° 1803.1415926 =0.2618=π/12 rad β=arctan(x/h)=arctan(30/15)1.1071 rad γ=α+β=0.2618+1.10711.3689 rad  γ2=180/π γ=180/3.1416 1.368978.4349    tan γ = (x+y)/h  y=h tanγx=15 tan1.368930=25 3=43.3 m



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