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Simplifying
3.14159265359r * r * 40 = 30000
Reorder the terms for easier multiplication:
3.14159265359 * 40r * r = 30000
Multiply 3.14159265359 * 40
125.6637061r * r = 30000
Multiply r * r
125.6637061r2 = 30000
Solving
125.6637061r2 = 30000
Solving for variable 'r'.
Move all terms containing r to the left, all other terms to the right.
Divide each side by '125.6637061'.
r2 = 238.7324147
Simplifying
r2 = 238.7324147
Take the square root of each side:
r = {-15.450968083, 15.450968083}
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