120 likes | 281 Views
10-1 Circles and Circumference. Circle. The locus of all points in a plane equidistant from a given point called the center . Circles are named by their center point Chord - any segment with endpoints on the circle Diameter - The chord passing through the center of the circle
E N D
Circle • The locus of all points in a plane equidistant from a given point called the center. • Circles are named by their center point • Chord- any segment with endpoints on the circle • Diameter- The chord passing through the center of the circle • Radius- a segment whose endpoints are the center of the circle and a point on the circle
Example: • Circle R has diameters ST and QM • If ST=18, find RS • If RM=24, find QM • If RN=2, find RP Q P S R T N M
Examples: • Diameter of x = 22, diameter of Y =16 and diameter of Z =10 • Find EZ and XF X Y Z E G F
Circumference • The distance around the circle • C = πd or C = 2πr (where π≈3.14, d is diameter and r is radius) Example: Find circumference if r = 13 inches
Example: • Find the EXACT circumference
Standard equation • For a circle with center (h, k) and radius r x and y are variables and must ALWAYS be in your answer!
Example: Write the equation of the circle • With center (-1, 3) and radius • With endpoints of the diameter (4, 6) and (-2, 6)
To graph a circle: • Find the center (h, k) (remember that the formula is x-h and y-k so when naming the center you do the opposite of the equation) Find the radius by taking the square root of the number after the = Plot the center and count out for the radius