# public Khan /khan-exercises

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  d3e71910 » spicyj  2011-06-01 Circles 1 exercise 1  7041f1ba » jeresig  2013-04-23 Re-run the linter on the exercises. 2 3  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 4  eced3734 » beneater  2012-04-12 Fix titles; rename area_of_squares_and_rectangles 5 Area of a circle  ac1415e8 » spicyj  2014-03-05 Use requirejs for module loading 6  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 7  d3e71910 » spicyj  2011-06-01 Circles 1 exercise 54 55  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 56
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Suppose the radius of a circle is \color{R_COLOR}{R}. What is its area?

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66  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 67
Math.PI * R * R
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 68 69  dd95925c » jeresig  2013-04-16 Run all the exercises through the cleaner. 70  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 71 initCircle( R ); 72 73 drawRadius( R ); 74
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We know K = \pi r^2, so K = \pi \cdot \color{R_COLOR}{R}^2 = \color{K_COLOR}{R * R\pi}.

77  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 78
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 79 drawArea( R ); 80 81 82 83 84 85 86 87 randRange(1, 8) 88 89 90  72429d81 » jeresig  2013-05-07 Re-run the exercises through the linter. 91 Suppose the area of a circle is \color{K_COLOR}{\pi}. What is its radius? Suppose the area of a circle is \color{K_COLOR}{R * R\pi}. What is its radius?  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 92
93  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 94
R
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 95 96  dd95925c » jeresig  2013-04-16 Run all the exercises through the cleaner. 97  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 98 initCircle( R ); 99 100 drawArea( R ); 101
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We know K = \pi r^2, so r = \sqrt{K / \pi} = \sqrt{\color{K_COLOR}{R * R\pi} / \pi} = \color{R_COLOR}{R}.

104  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 105
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 106 drawRadius( R ); 107 108 109 110 111 112 113 114 randRange(1, 8) 115 116 117 118 Suppose the diameter of a circle is \color{D_COLOR}{2 * R}. What is its area? 119 120  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 121 Math.PI * R * R  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 122 123
 dd95925c » jeresig  2013-04-16 Run all the exercises through the cleaner. 124
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 125 initCircle( R ); 126 127 drawDiameter( R ); 128 129 First, find the radius: r = d/2 = \color{D_COLOR}{2 * R}/2 = \color{R_COLOR}{R}. 130 131 Now find the area: K = \pi r^2, so K = \pi \cdot \color{R_COLOR}{R}^2 = \color{K_COLOR}{R * R\pi}. 132  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 133  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 134 drawArea( R ); 135
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 72429d81 » jeresig  2013-05-07 Re-run the exercises through the linter. 146

Suppose the area of a circle is \color{K_COLOR}{\pi}. What is its diameter?

Suppose the area of a circle is \color{K_COLOR}{R * R\pi}. What is its diameter?

 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 147 148  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 149 2 * R  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 150 151
 dd95925c » jeresig  2013-04-16 Run all the exercises through the cleaner. 152
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 153 initCircle( R ); 154 155 drawArea( R ); 156 157 First, find the radius: K = \pi r^2, so r = \sqrt{K / \pi} = \sqrt{\color{K_COLOR}{R * R\pi} / \pi} = \color{R_COLOR}{R}. 158 159 Now find the diameter: d = 2r = 2\cdot \color{R_COLOR}{R} = \color{D_COLOR}{2*R}. 160  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 161  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 162 drawDiameter( R ); 163
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Suppose the circumference of a circle is \color{C_COLOR}{2 * R\pi}. What is its area?

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176  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 177
Math.PI * R * R
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 178 179  dd95925c » jeresig  2013-04-16 Run all the exercises through the cleaner. 180  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 181 initCircle( R ); 182 183 drawCircumference( R ); 184
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First, find the radius: r = c/2\pi = \color{C_COLOR}{2 * R\pi}/2\pi = \color{R_COLOR}{R}.

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Now find the area: K = \pi r^2, so K = \pi \cdot \color{R_COLOR}{R}^2 = \color{K_COLOR}{R * R\pi}.

188  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 189
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 190 drawArea( R ); 191 192 193 194 195 196 197 198 randRange(1, 8) 199 200 201  72429d81 » jeresig  2013-05-07 Re-run the exercises through the linter. 202 Suppose the area of a circle is \color{K_COLOR}{\pi}. What is its circumference? Suppose the area of a circle is \color{K_COLOR}{R * R\pi}. What is its circumference?  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 203
204  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 205
Math.PI * 2 * R
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$for exercises 206 207  dd95925c » jeresig  2013-04-16 Run all the exercises through the cleaner. 208  4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->$ for exercises 209 initCircle( R ); 210 211 drawArea( R ); 212
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First, find the radius: K = \pi r^2, so r = \sqrt{K / \pi} = \sqrt{\color{K_COLOR}{R * R\pi} / \pi} = \color{R_COLOR}{R}.

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Now find the circumference: c = 2\pi r = 2\pi \cdot \color{R_COLOR}{R} = \color{C_COLOR}{2*R\pi}.

216  c6949fe0 » jeresig  2013-04-17 Running the clean-exercises.py script against the exercises. 217
 4e4cb9b1 » beneater  2012-04-10 lint: tabs->spaces and jQuery->\$ for exercises 218 drawCircumference( R ); 219
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 7041f1ba » jeresig  2013-04-23 Re-run the linter on the exercises. 225 226
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