Circumference and Area of a Circle and a Sector
Learn how to find circumference and area of a circle, and calculate arc length and sector area. Let’s get started! 🚀
Video Lesson
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Flashcards
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🛎️ π and Circumference
- π is a number used in circle formulas and is usually rounded to 3.14 in calculations.
- The formula for circumference is C = πd or C = 2πr.
🛎️ Finding the Circumference of a Circle
- If the radius is 5 cm, substitute into C = 2πr.
- This gives C = 10π cm, which is approximately 31.4 cm.
🛎️ Finding the Area of a Circle
- The formula for circle area is A = πr².
- If the radius is 3 cm, the area is 9π cm², about 28.26 cm².
🛎️ Circle Sectors
- A sector is a fraction of a circle based on the central angle.
- Use α/360 × 2πr for arc length and α/360 × πr² for area.
Practice Questions
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Interactive Activity
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