 Question

secondary 4 | A Maths

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Clarence Tang

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Challenging question for functions.

Date Posted: 2 months ago
Views: 22
Eric Nicholas K
2 months ago
The ‘curve’ has a minimum point. We can draw our axes from the ground level below that point so that we can draw out the graph or find out the equation.
J
2 months ago
Looking at the curve, you can use a typical quadratic curve equation of the form
y = ax² + bx + c

In this case, since we are measuring x from the centre, , the midpoint of the curve is on the y axis. So the value of b is 0.

Lowest height of the cable = 80m.

At the centre, x = 0, then y = c .
Since lowest height is 80m, c = 80.

If the two 200m-high towers are 1200m, then distance from the centre to either tower is half of it
= 600m

This also tells you that
y = 200 when x = 600 or -600

We can now come up with the following :
y = ax² + 80

Sub y = 200, x = 600(or -600, up to you)

200 = a(600²) + 80

200 = 360000a + 80

120 = 360000a

a = 120/360000
a = 1/3000
Clarence Tang
1 month ago
Thanks J! This helped me a lot in understanding this problem!
J
1 month ago
Welcome! 