Problem: the perimeter of a triangle is 40 cm and the inradius of the triangle is 2.5 cm . what is the area of the triangle
Rationale: "explanation : area of a triangle = r * s where r is the inradius and s is the semi perimeter of the triangle . area of triangle = 2.5 * 40 / 2 = 50 cm 2 answer : option c"
annotated_formula: triangle_area(2.5, 40)