Question 1208494
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Answer: <font color=red>53.6 feet</font>


Explanation
The forest ranger in the tower is at point C.
His eyeline is initially aimed along the dashed line. Then he rotates his view 40 degrees downward since this is the angle of depression. 
The other ranger is at point B.
{{{
drawing(400,400,-5,5,-5,5,

circle(-2,-2,0.05),circle(-2,-2,0.07),circle(-2,-2,0.09),circle(-2,-2,0.11),circle(2,-2,0.05),circle(2,-2,0.07),circle(2,-2,0.09),circle(2,-2,0.11),circle(-2,2,0.05),circle(-2,2,0.07),circle(-2,2,0.09),circle(-2,2,0.11),

line(-2,-2,2,-2),line(2,-2,-2,2),line(-2,2,-2,-2),

line(-2,2,-1.8,2),line(-1.6,2,-1.4,2),line(-1.2,2,-1,2),line(-0.8,2,-0.6,2),line(-0.4,2,-0.2,2),line(0,2,0.2,2),line(0.4,2,0.6,2),line(0.8,2,1,2),line(1.2,2,1.4,2),line(1.6,2,1.8,2),

line(-2,-1.8,-1.8,-1.8),line(-1.8,-1.8,-1.8,-2),

locate(-2.2,-2.2,"A"),locate(1.8,-2.2,"B"),locate(-2.2-0.2,1.8,"C"),
locate(-0.4,-2.2,"x"),locate(-2.8,0,"45"),locate(-1,1+0.8,40^o),locate(-1.5-0.3,0.8+0.5,50^o),

locate(-4.5,-3.5,matrix(1,4,"Diagram","not","to","scale"))

)
}}}
Note in the diagram that 50+40 = 90.
Or you could say 90-40 = 50 so you find that other angle near point C.


Once that 50 degree angle is found, erase the dashed line and erase the 40 degree angle. 
We focus entirely on triangle ABC.
{{{
drawing(400,400,-5,5,-5,5,

circle(-2,-2,0.05),circle(-2,-2,0.07),circle(-2,-2,0.09),circle(-2,-2,0.11),circle(2,-2,0.05),circle(2,-2,0.07),circle(2,-2,0.09),circle(2,-2,0.11),circle(-2,2,0.05),circle(-2,2,0.07),circle(-2,2,0.09),circle(-2,2,0.11),

line(-2,-2,2,-2),line(2,-2,-2,2),line(-2,2,-2,-2),

line(-2,-1.8,-1.8,-1.8),line(-1.8,-1.8,-1.8,-2),

locate(-2.2,-2.2,"A"),locate(1.8,-2.2,"B"),locate(-2.2-0.2,1.8,"C"),
locate(-0.4,-2.2,"x"),locate(-2.8,0,"45"),locate(-1.5-0.3,0.8+0.5,50^o),

locate(-4.5,-3.5,matrix(1,4,"Diagram","not","to","scale"))

)
}}}

It's a right triangle, so you can use the tangent ratio to find the distance from A to B.
tan(angle) = opposite/adjacent
tan(C) = AB/AC
tan(50) = x/45
x = 45*tan(50)
x = 53.628911666739 feet approximately
x = <font color=red>53.6 feet</font> when rounding to the nearest tenth.
Please make sure that your calculator is set to degrees mode.
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