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Five-Minute Check (over Lesson 12–6) Then/Now New Vocabulary Key Concept: Lines in Plane and Spherical Geometry Example 1: Describe Sets of Points on a Sphere Example 2: Real-World Example: Identify Lines in Spherical Geometry Example 3: Compare Plane Euclidean and Spherical Geometries Lesson Menu

Find the surface area of the sphere. Round to the nearest tenth. A. 201.1 in2 B. 223.5 in2 C. 251.9 in2 D. 268.1 in2 5-Minute Check 1

Find the surface area of the sphere. Round to the nearest tenth. A. 1107 ft2 B. 1256.6 ft2 C. 3987.1 ft3 D. 4188.8 ft3 5-Minute Check 2

Find the volume of the hemisphere. Round to the nearest tenth. A. 2237.8 cm2 B. 2412.7 cm2 C. 8578.6 cm3 D. 9006.1 cm3 5-Minute Check 3

Find the volume of the hemisphere. Round to the nearest tenth. A. 680.6 mm2 B. 920.8 mm2 C. 1286.2 mm3 D. 1294.3 mm3 5-Minute Check 4

Find the surface area of a sphere with a diameter of 14 Find the surface area of a sphere with a diameter of 14.6 feet to the nearest tenth. A. 637.4 ft2 B. 669.7 ft2 C. 1428.8 ft2 D. 1629.5 ft3 5-Minute Check 5

A hemisphere has a great circle with circumference approximately 175 A hemisphere has a great circle with circumference approximately 175.84 in2. What is the surface area of the hemisphere? A. 4926.0 in2 B. 7381.5 in2 C. 19,704.1 in2 D. 39,408.1 in2 5-Minute Check 6

You identified basic properties of spheres. Describe sets of points on a sphere. Compare and contrast Euclidean and spherical geometries. Then/Now

non-Euclidean geometry spherical geometry non-Euclidean geometry Vocabulary

Concept

A. Name two lines containing R on sphere S. Describe Sets of Points on a Sphere A. Name two lines containing R on sphere S. Answer: AD and BC are lines on sphere S that contain point R. Example 1A

B. Name a segment containing point C on sphere S. Describe Sets of Points on a Sphere B. Name a segment containing point C on sphere S. Answer: GK Example 1B

C. Name a triangle on sphere S. Describe Sets of Points on a Sphere C. Name a triangle on sphere S. Answer: ΔKGH Example 1C

A. Determine which line on sphere Q does not contain point P. A. TL B. VM C. PS D. RO Example 1A

B. Determine which segment on sphere Q does not contain point N. A. LO B. MS C. NV D. SO Example 1B

C. Name a triangle on sphere Q. A. ΔVSU B. ΔPRU C. ΔNSU D. ΔNOM Example 1

Answer: No; it is not a great circle. Identify Lines in Spherical Geometry SPORTS Determine whether the line h on the basketball shown is a line in spherical geometry. Explain. Notice that line h does not go through the poles of the sphere. Therefore line h is not a great circle and so not a line in spherical geometry. Answer: No; it is not a great circle. Example 2

A. Yes, it is a line in spherical geometry. SPORTS Determine whether the line X on the basketball shown is a line in spherical geometry. A. Yes, it is a line in spherical geometry. B. No, it is not a line in spherical geometry. Example 2

If two lines are parallel, they never intersect. Compare Plane Euclidean and Spherical Geometries A. Tell whether the following postulate or property of plane Euclidean geometry has a corresponding statement in spherical geometry. If so, write the corresponding statement. If not, explain your reasoning. If two lines are parallel, they never intersect. Answer: True; given a line, the only line on a sphere that is always the same distance from the line is the line itself. Example 3A

Any two distinct lines are parallel or intersect once. Compare Plane Euclidean and Spherical Geometries B. Tell whether the following postulate or property of plane Euclidean geometry has a corresponding statement in spherical geometry. If so, write the corresponding statement. If not, explain your reasoning. Any two distinct lines are parallel or intersect once. Answer: False; two distinct lines on a sphere intersect twice. Example 3B

Perpendicular lines intersect at exactly one point. Tell whether the following postulate or property of plane Euclidean geometry has a corresponding statement in spherical geometry. Perpendicular lines intersect at exactly one point. A. This holds true in spherical geometry. B. This does not hold true in spherical geometry. Example 3A

It is possible for two circles to be tangent at exactly one point. Tell whether the following postulate or property of plane Euclidean geometry has a corresponding statement in spherical geometry. If so, write the corresponding statement. If not, explain your reasoning. It is possible for two circles to be tangent at exactly one point. A. This holds true in spherical geometry. B. This does not hold true in spherical geometry. Example 3B

End of the Lesson