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Section 7.4: Circumference and Area of a Circle. Postulate 22: The ratio of the circumference of a circle to the length of its diameter is a unique positive constant. (pi) is the ratio between the circumference C and the diameter length of any circle; thus = C/d in any circle .
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Section 7.4:Circumference and Area of a Circle • Postulate 22: The ratio of the circumference of a circle to the length of its diameter is a unique positive constant. • (pi) is the ratio between the circumference C and the diameter length of any circle; thus = C/d in any circle. Section 7.4 Nack
Length of an Arc • Distance between the endpoints of the arc as though it was measured along a straight line. • Theorem 7.4.2: In a circle whose circumference is C, the length l of an arc whose degree measure m is given by: l = m C 360 Example 4 p. 368 Figure 7.47 • Limits: an approximation of an upper or lower numerical value. See Example 5 Section 7.4 Nack
Area of a Circle • Theorem 7.4.3: The area A of a circle whose radius has length r is given by A = r² • Ring: A plane figure bounded by concentric circles. Example 8 p. 370 Section 7.4 Nack