a rope of which a calf is tied is increased from 10 m to 20 m , how much additional grassy ground shall it graze ?
"π ( 202 – 102 ) = 942.86 answer : e"
multiply(subtract(power(20, const_2), power(10, const_2)), divide(add(multiply(10, const_2), const_2), add(const_4, const_3)))