A bridge is built in the shape of

Joselito Cueto

Joselito Cueto

Answered question

2022-10-02

A bridge is built in the shape of a parabolic arc and is to have a span of 100 feet. The height of the arch at a distance of 40 feet from the center is to be 10 feet. Assume that the ground is the x-axis and the y-axis as the axis of the arc.

a. How high is the arch at its center approximated in two decimal places?

b. What is the horizontal length, approximated to two decimal places, of the arch from axis when it’s 15 feet high?

 

Answer & Explanation

alenahelenash

alenahelenash

Expert2023-05-29Added 556 answers

To solve this problem, we can start by setting up the equation for a parabolic arc. The general equation for a parabola is given by:
y=ax2+bx+c
In this case, since the ground is the x-axis and the y-axis is the axis of the arc, we can assume that the vertex of the parabola is at the origin (0, 0). This means that the equation can be simplified to:
y=ax2
To find the specific equation for the bridge, we need to use the given information. We know that the height of the arch at a distance of 40 feet from the center (which is the x-coordinate of the vertex) is 10 feet. Let's use this information to find the value of a.
Substituting the values (40, 10) into the equation, we get:
10=a·(40)2
Simplifying the equation, we have:
10=a·1600
Now, let's solve for a:
a=101600
Simplifying the fraction, we have:
a=1160
So the equation of the parabolic arc is:
y=1160x2
Now, let's proceed to answer the questions.
a. How high is the arch at its center, approximated to two decimal places?
The center of the bridge is at x = 0. To find the height at the center, we substitute x = 0 into the equation:
y=1160(0)2
Simplifying, we get:
y=1160·0
y=0
Therefore, the height of the arch at its center is 0 feet.
b. What is the horizontal length, approximated to two decimal places, of the arch from the axis when it's 15 feet high?
To find the horizontal length, we need to solve the equation for x when y = 15. Let's substitute y = 15 into the equation:
15=1160x2
To isolate x, we can multiply both sides of the equation by 160:
2400=x2
Taking the square root of both sides, we have:
x=2400
x48.99
Therefore, the horizontal length of the arch from the axis when it's 15 feet high, approximated to two decimal places, is approximately 48.99 feet.

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