Girl I got you
The way I would do this might be a little different from the way you might do it but we learn to make our own formulas cuz it would help us remember better So we have a 7 sided regular polygon and the "radius" given the way i would do this is turn the 7 sided polygon into 7 triangles like shown in the attachment, the other side of the triangle will be 7.74 as well as it is an isosceles triangle and the angle we can find out by dividing 360 by 7 as 360 is the total angle and we divided it into 7 different triangles so that would be 51.43
so now we have a triangle with 2 sides and an angle we can easily apply the formula for area of triangle which is
we have a, b and angle C so
Now just simplify is :)
we now have the area of one triangle now all you do is multiply it with 7
There you go, you have your answer :) 163.9
Hope this helps, I know this looks really complicated but trust me its really simple, if you have any issue just reply :)