2 θ 10 meters; = 1 radian; = 1 A r 71. 2θ 2 2 θ = 1 radian; 81. = = 10 ⋅ 1 = 5 s rθ 3 = 2 ft A = r 2 meters 72. θ = 6 feet; = 2 radian; = = 6 ⋅ 2 = 12 2 = 1 ⎛ 1 ⎞ r s rθ r feet 2 2 = 1 r θ = 1 radian; = 2 feet; s 3 2 73. 6 2 ⎜ ⎟ ⎝ ⎠ = s rθ = 12 r = = = 2 6 r s = r = ≈ 12 2 3 3.464 feet feet (1/ 82. θ 3) θ = 1 radian; 4 = 6 cm2 A = s rθ 74. θ = 1 radian; = 1 A r 4 = 6 cm; 2 s 2θ = = r s = ⎛ ⎞ 6 1 1 r 2 6 = 24 cm (1/ θ 4) = 6 1 r ⎝ ⎠ 4 2 2 75. = = 5 miles; 3 miles; 8 r s 2 = s rθ = 48 r θ = = 3 = 0.6 s = r 48 = 4 3 ≈ 6.928 cm radian 5 r = 5 miles; r 83. = 3 mi2 A 76. = 6 meters; = 8 meters; 1 r s 2 = s rθ = θ A r 2 θ = = 8 = 4 ≈ 1.333 s (5)2 = θ 3 1 radians 6 3 = r 3 25 θ 2 inches; 77. θ = = ⋅ = π 30º 30 radian; 2 = 2 r π 180 6
71. r = 10 meters; θ = 1 radian; 2 s = rθ = 10 ⋅ 1 = 5 meters 2 81. θ = 1 radian; 3 A = 1 r 2θ 2 A = 2 ft 2 72. r = 6 feet; θ = 2 radian; s = rθ = 6 ⋅ 2 = 12 feet 2 = 1 r 2 ⎛ 1 ⎞ 73. θ = 1 radian; s = 2 feet; 3 ⎜ ⎟ ⎝ ⎠ 2 = 1 r 2 6 2 s = rθ r = s = 2 = 6 feet 12 = r r = 12 = 2 3 ≈ 3.464 feet θ (1/ 3) 82. θ = 1 radian; 4 A = 6 cm2 74. θ = 1 radian; 4 s = rθ s = 6 cm; A = 1 2 r 2θ r = s = 6 = 24 cm 6 = 1 r 2 ⎛ 1 ⎞ θ (1/ 4) 2 6 = 1 r 2 ⎝ 4 ⎠ 75. r = 5 miles; s = 3 miles; 8 2 s = rθ θ = s = 3 = 0.6 radian 48 = r r = 48 = 4 3 ≈ 6.928 cm r 5 83. r = 5 miles; A = 3 mi2 76. r = 6 meters; s = 8 meters; 1 2 s = rθ θ = s = 8 = 4 ≈ 1.333 radians A = r θ 2 3 = 1 (5)2 θ r 6 3 2 3 = 25 θ 77. r = 2 inches; θ = 30º = 30 ⋅ π = π radian; 2 180 6