Problem: the sector of a circle has radius of 21 cm and central angle 108 o . find its perimeter ?
Rationale: "perimeter of the sector = length of the arc + 2 ( radius ) = ( 108 / 360 * 2 * 22 / 7 * 21 ) + 2 ( 21 ) = 39.6 + 42 = 81.6 cm answer : a"
annotated_formula: multiply(multiply(const_2, divide(multiply(subtract(21, const_3), const_2), add(const_4, const_3))), 21)