The diameter of a CD is 11.43 so the radius is 5.715.
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Draw the circle O, and the chord AB. From the center, draw the radius OC which passes though the midpoint, D, of AB. Since the radius OC bisects the chord AB, it is perpendicular to AB. So that CD is the required height, whose length equals to the difference of the length of the radius OC and the length of its part OD. Draw the radius OA and OB. So that OD is the median and the height of the isosceles triangle AOB, whose length equals to √(r2 - AB2/4) (by the Pythagorean theorem). Thus, the length of CD equals to r - √(r2 - AB2/4).
It means to multiply the radius by itself: radius x radius
C = Pi * d 28.26 cm = 3.1415 * d d = 28.26 cm/3.1415 d = 8.9954 r = d/2 r = 8.9954 cm/2 4.4977 cm The radius of a CD with a circumference of 28.26 cm is about 4.50 cm.
When you try to figure out an area of a circle, you square the radius, then multiply it by pi to get the area of a circle. A radius square is radius x radius, or radius squared.
A regular CD has a diameter of about 4.75 inches, which means it has a radius of about 2.375 inches. The area of a circle is calculated using the formula A = πr^2, so the area of a regular CD is approximately 17.67 square inches. So, there you have it, the sassy answer to your CD area question.