+130516 1. True.....by definition....a diameter touches two points on circle...thus...it is a chord
2. False .....a chord touches two points on a circle.....a radius does not
3. True......this is the definition of a chord
4. True.......congruent chords span congruent arcs.....
5. True.......congruent arcs are spanned by congruent chords
6. If the chords spanning the arcs are congruent, then the arcs are congruent. Also, if the central angles intercepting the chord endpoints are equal, then the arcs are congruent.
7. All semi-circles in the same circle are congruent.......they are spanned by equal diameters
8. arc AB = 70° arc AC = 130°
9. Lenth of arc AB = 2pi(3)* [70/360] = 6pi * [ 70/360] = about 3.67 units
