An arc on a circle measures [tex]$85^{\circ}$[/tex]. The measure of the central angle, in radians, is within which range?

A. 0 to [tex]$\frac{\pi}{2}$[/tex] radians
B. [tex]$\frac{\pi}{2}$[/tex] to [tex]$\pi$[/tex] radians
C. [tex]$\pi$[/tex] to [tex]$\frac{3\pi}{2}$[/tex] radians
D. [tex]$\frac{3\pi}{2}$[/tex] to [tex]$2\pi$[/tex] radians



Answer :

To determine the measure of the central angle in radians and its range, follow the steps below:

1. Convert the angle from degrees to radians:
- We know that [tex]\(1 \text{ degree} = \frac{\pi}{180} \text{ radians}\)[/tex].
- Therefore, to convert [tex]\(85^\circ\)[/tex] to radians, we use the conversion factor:
[tex]\[ 85^\circ \times \frac{\pi}{180} = \frac{85\pi}{180} \][/tex]
- Simplify [tex]\(\frac{85\pi}{180}\)[/tex]:
[tex]\[ \frac{85\pi}{180} = \frac{17\pi}{36} \approx 1.4835298641951802 \text{ radians} \][/tex]

2. Determine the range within which the angle in radians falls:
- We compare [tex]\(1.4835298641951802\)[/tex] radians with the given boundaries:
- [tex]\(0 \text{ to } \frac{\pi}{2}\)[/tex] radians
- [tex]\(\frac{\pi}{2} \text{ to } \pi\)[/tex] radians
- [tex]\(\pi \text{ to } \frac{3\pi}{2}\)[/tex] radians
- [tex]\(\frac{3\pi}{2} \text{ to } 2\pi\)[/tex] radians

- Knowing that [tex]\(\frac{\pi}{2} \approx 1.5708\)[/tex] and [tex]\(\pi \approx 3.1416\)[/tex], we can see that the value [tex]\(1.4835298641951802\)[/tex] radians falls within:
[tex]\[ 0 \text{ to } \frac{\pi}{2} \text{ radians} \quad \text{(since 0 ≤ 1.4835298641951802 < 1.5708)} \][/tex]

So, the measure of the central angle [tex]\(85^\circ\)[/tex] in radians is approximately [tex]\(1.4835298641951802\)[/tex], and it falls within the range [tex]\(0 \text{ to } \frac{\pi}{2} \text{ radians}\)[/tex].