# What's normal about a circle

## Understanding Mathematics 1, workbook

200 a) Z b) Z 8 Circle and parts of a circle 201 All points of a circle line k have the same distance from the center M of the circle, namely the radius r. The distance from circle edge to circle edge through M is called the diameter d. The points X, Y and Z lie on k. 202 2) r = 3 cm, d = 6 cm 203 a) d = 50mm b) d = 6 cm 204 MBAFEDGHC points that are the same distance from M as A: B, D, F, G points that one have a smaller distance to M like A: C, H points that have a larger distance to M like A: E 205 A line that connects two points of a circular line is called a circular chord s in two arcs b 1 and b 2. The two arcs are always longer than the corresponding chord. 206 a) MS s 1 s 2 b) ZB: 207 s = 14 cm 208 a) 1 b) 0 c) 2 d) 0 e) 1 f) 0 209 ZB: M k 1 k 3 k 4 k 2 210 a ) M 2 M 1 k 2 k 1 b) ZB: 211 a) M 2 M 1 k 2 k 1 b) ZB: M 2 M 1 k 2 k 1 212 The straight line g 1 intersects the circular line k at two points A and B. One calls g 1 a circle edge. The straight line g 2 touches the circular line k at a point P. We call g 2 a circle tangent. It is normal to MP = r. The straight line g 3 has no points in common with the circular line k. One calls g 3 a passer-by in a circle. 213 a) ZB: b) ZB: c) ZB: M kp 1 p 2 M ks 1 s 2 M kt 1 t 2 214 a) ZB: b) ZB: c) ZB: M gk 1 M gk 2 M k 3 g 215 Eg: A circle line is the outermost boundary of a circular area and can be drawn with a compass mine. A circular area is the inner area of ​​a circle to which the circular line also belongs; the circular area can be painted. 216 The area between the circular lines of two concentric circles is a circular ring (r 1 ≠ r 2). The area between a chord s and an arc b is a segment of a circle. The area between two radii and an arc b is a sector of a circle with the central angle α. 217 M k 1 k 2 M S s M 2 M 1 k 2 k 1 Solutions: 8 Circle and parts of a circle 10 For testing purposes only - property of the publisher öbv