4-2: Chords and Arcs4-2: Chords and Arcs4-2: Chords and Arcs4-2: Chords and Arcs

Unit 4: CirclesUnit 4: CirclesEnglish CasbarroEnglish Casbarro

Just like segments and angles, arcs have an addition postulate:

When you need the distance measurement (not the degree measurement) of an arc, you are finding the portion of the circumference that the arcintersects. The formula, then, is: 2πr (the circumference) times the degree measure /360° (the portion of the circle that contains the arc).

******Think: What is the difference between arc measure and arc length?

Turn in the following problems1. Chantal’s bike has wheels with a 27 in diameter. a. What are AC and AD if DB is 7 in.? b. What is CD to the nearest tenth of an inch? c. What is CE, the length of the top of the bike stand?

2. In the figure at the right, sphere O with radius 13 cm is intersected by a plane 5 cm from the center O. Find the radius of the cross section A.

3. A plane intersects a sphere with radius 10 cm forming the cross section B with radius 8 in. How far is the plane from the center of the sphere?