Given the task definition and input, reply with output. In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: the perimeter of a triangle is 40 cm and the in radius of the triangle is 2.5 cm . what is the area of the triangle ? 
Options: a ) 76 , b ) 88 , c ) 66 , d ) 55 , e ) 50

e