Mathematics (AS)·Circular measure · NSSCAS 1.5.1
Radians, arc length & sector area
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In this lesson you will meet the radian — the natural way mathematicians measure angles. You will learn to change between degrees and radians in both directions, and to recall the exact radian values of the famous angles. Then you will use the two golden formulae, s equals r theta and A equals a half r squared theta, to find arc lengths, sector areas, sector perimeters and even the area of a segment. By the end you will handle any circular measure exam question with confidence.
What you'll learn in this lesson
By the end you should be able to (NSSCAS Mathematics (AS) 1.5.1):
- Interpret the term radian and use the relationship between radians and degrees to convert angles in both directions.
- Use the formulae s = rθ and A = ½r²θ to solve problems involving the arc length, sector area and segment area of a circle.
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