a parabolic arch has a span of 120 feet and a maximum height of 25 feet.choose suitable rectangular coordinate axes and find the equation of the parabola.then calculate the height of the arch at points 10 feet,20 feet,and 40 feet from the centre.
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a parabolic arch has a span of 120 feet and a maximum height of 25 feet.choose suitable rectangular coordinate axes and find the equation of the parabola.then calculate the height of the arch at points 10 feet,20 feet,and 40 feet from the centre.
a parabolic arch has a span of 120 feet and a maximum height of 25 feet.choose suitable rectangular coordinate axes and find the equation of the parabola.then calculate the height of the arch at points 10 feet,20 feet,and 40 feet from the centre.
a parabolic arch has a span of 120 feet and a maximum height of 25 feet.choose suitable rectangular coordinate axes and find the equation of the parabola.then calculate the height of the arch at points 10 feet,20 feet,and 40 feet from the centre.
Let the equation of the parabola:y=ax²+bx+c
In accordance with the establishment of coordinates shown in Figure
When x = 0, y = 25, so c = 25
When y = 0, x = -60 or x = 60,
3600a+60b +25 = 0
3600a-60b +25 = 0
To be: a = -1/144, b = 0
Therefore, the parabola equation is: y =- x^2/144 +25
When x = 10, y = 25-5/72
When x = 20, y = 25-5/36
When x = 40, y = 25-5/18
抛物线拱有120英尺宽，最大高度25英尺。选择合适的直角坐标轴，并找到了抛物线方程。然后计算距离市中心在10英尺，20英尺，40英尺拱的高度。
以最高点为原点建立坐标系。y=ax平方+bx+c(a不等于0)
原点坐标带入 c=0 对称轴带入 b=0
x=60时 y=-25
a=-1/144
所以，方程为：y=-1/144x平方
x=10时...
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抛物线拱有120英尺宽，最大高度25英尺。选择合适的直角坐标轴，并找到了抛物线方程。然后计算距离市中心在10英尺，20英尺，40英尺拱的高度。
以最高点为原点建立坐标系。y=ax平方+bx+c(a不等于0)
原点坐标带入 c=0 对称轴带入 b=0
x=60时 y=-25
a=-1/144
所以，方程为：y=-1/144x平方
x=10时，y=-25/36 即：拱高为25/36
x=20时，y=-25/9 即：拱高为25/9
x=40时，y=-100/9 即：拱高为100/9
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