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Calculate Central Angle in Radians Given Sector Arc Length and Radius
Mathematics
Grade 10 of Junior High School
Question Content
If the arc length of a sector is 3π cm and its radius is 12cm, then what is the central angle in radians?
Correct Answer
$\\frac{\\pi}{4}$ radians
Detailed Solution Steps
1
Step 1: Recall the formula for arc length of a sector: $l = r\\theta$, where $l$ is arc length, $r$ is radius, and $\\theta$ is the central angle in radians.
2
Step 2: Substitute the given values $l=3\\pi$ cm and $r=12$ cm into the formula: $3\\pi = 12\\theta$.
3
Step 3: Solve for $\\theta$: $\\theta = \\frac{3\\pi}{12} = \\frac{\\pi}{4}$ radians.
Knowledge Points Involved
1
Arc Length Formula for Sectors (Radians)
The formula $l = r\\theta$ relates the arc length $l$ of a sector, the radius $r$ of the circle, and the central angle $\\theta$ measured in radians. It is derived from the definition that 1 radian is the angle subtended by an arc equal in length to the radius, so the ratio of arc length to radius equals the radian measure of the angle.
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