17. A piece of wire is in the form of an arc of a circle with a radius of [tex]10.5 \, \text{m}[/tex]. Find the length of the wire given that the angle at the center of the arc is [tex]150^{\circ}[/tex]. Take [tex]\pi = \frac{22}{7}[/tex].

(4 marks)



Answer :

To determine the length of a wire that forms an arc of a circle with a radius of [tex]\(10.5\)[/tex] meters and a central angle of [tex]\(150^\circ\)[/tex], follow these steps:

1. Convert the angle from degrees to radians:
The formula to convert degrees to radians is:
[tex]\[ \text{radians} = \text{degrees} \times \left(\frac{\pi}{180}\right) \][/tex]
Given:
[tex]\[ \text{angle in degrees} = 150^\circ \][/tex]
Use [tex]\(\pi = \frac{22}{7}\)[/tex]:
[tex]\[ \text{angle in radians} = 150 \times \left(\frac{22}{7 \times 180}\right) \][/tex]

2. Angle conversion:
Simplify the angle conversion:
[tex]\[ \text{angle in radians} = 150 \times \left(\frac{22}{1260}\right) = 150 \times \frac{11}{630} = 150 \times \frac{1}{60} = 2.5 \text{ radians} \][/tex]

3. Calculate the length of the arc:
The length [tex]\(S\)[/tex] of an arc is given by the formula:
[tex]\[ S = r \theta \][/tex]
where [tex]\(r\)[/tex] is the radius and [tex]\(\theta\)[/tex] is the angle in radians. Given:
[tex]\[ r = 10.5 \, \text{meters} \][/tex]
and from the previous step,
[tex]\[ \theta = 2.619047619047619 \, \text{radians} \][/tex]

4. Compute the arc length:
Substitute the values into the formula:
[tex]\[ S = 10.5 \times 2.619047619047619 \][/tex]

5. Simplify the expression:
Compute:
[tex]\[ S = 27.5 \, \text{meters} \][/tex]

Hence, the length of the wire is [tex]\(27.5\)[/tex] meters.