Answer:
Area of Pentagon is directly proportional to side square
soooooo
A1/A2 = s1^2 / s2^2 = 16/49 = 4^2/ 7^2
sooo
s1/s2 = 4/7
As S1= 12cm
then
s2= 12 × 7/4 = 84/4= 21 cm
