how to calculation object length

hey guys!

i need to calculate some object shape length lets say ( pizza outline shape )

corel can only show the length but u cant edit or change it..

so any idea of how to do it for ex : 

i want a 100cm length ,, i only can change height and width

so i put like 

20cm h and 15 w it give me 100cm length..

anyway to calculate it ? any apps or something ??