Answer:
A. 72cm
Explanation:
Figure a is a convex pentagon, a convex pentagon is a pentagon that does not have an internal angle greater than
![{180}^(0)](https://img.qammunity.org/2021/formulas/mathematics/high-school/s3t7q9ssv0z1dv6tlf0t772bpjfimb02ry.png)
An easier thing to remember is that it does not have an angle pointing inwards like b, none of its angles/edges point toward the shape/inside