Step 1 :The equation of an ellipse centered at the origin with a horizontal major axis is given by: \(\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1\)
Step 2 :In this case, a = 138/2 = 69 feet and b = 25/2 = 12.5 feet. So the equation of the ellipse is: \(\frac{x^2}{69^2} + \frac{y^2}{12.5^2} = 1\)
Step 3 :We want to find the x-coordinate when the height y = 14.8 feet. Substituting y = 14.8 into the equation gives: \(\frac{x^2}{69^2} + \frac{14.8^2}{12.5^2} = 1\)
Step 4 :Solving for x^2 gives: \(x^2 = 69^2 * (1 - \frac{14.8^2}{12.5^2})\)
Step 5 :Taking the square root of both sides (and noting that x can be positive or negative because we're measuring distance from the center of the arch), we get: \(x = \pm69 * \sqrt{1 - \frac{14.8^2}{12.5^2}}\)
Step 6 :Calculating this gives: \(x = \pm69 * \sqrt{1 - \frac{219.04}{156.25}}\)
Step 7 :Simplifying further gives: \(x = \pm69 * \sqrt{1 - 1.401}\)
Step 8 :Solving for x gives: \(x = \pm69 * \sqrt{-0.401}\)
Step 9 :Since we can't have a negative square root in real numbers, it means that the height of 14.8 feet is not achievable in this ellipse. There seems to be a mistake in the problem as the maximum height of the ellipse is 12.5 feet, so it can't reach 14.8 feet. \(\boxed{\text{Error in the problem}}\)