Hi help me please, I can't seem to figure this one out

x= 2.73cm

1cm : 0.6828 = 4cm : 2.73cm

For the same angle we just work out 1cm first.

a^2+ b^2= c^2

0.82^2 + b^2 = 1^2 = changing to units 10

6.724 + b^2 = 10

10-6.724 = 2.276

Then x 3 and change units down by 10= 0.6828  

Step-by-step explanation:

Below shows why we must convert to mm from cm

a^2+ b^2= c^2

0.82^2 + b^2 = 1^2 =

0.6724 + b^2 = 1

1 - 0.6724 = b = 0.2276

0.2276 x 3 = 0.6828 cm

the correct is answer is a 9-sided polygon!