Question 1208256
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A two-lane road tunnel with a semicircular arch is 24 meters in diameter. 
The height of the tunnel at the end of each lane is √2/11meters. 
Determine the length of the road lanes. Give the coordinates or graph it
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Place the origin of the coordinate system at the ground level, at the middle 
of the diameter of the tunnel.


You will have semicircle with the radius 24/2 = 12 m.


An equation for this semicircle is  

    x^2 + y^2 = 12^2,

or

    x^2 = 144 - y^2.


Now substitute the given value of y into this formula and find x.
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Strictly follow my instruction at every your step.