You just need to plug those expressions inside the formula: it doesn't matter if they're expressions involving a variable instead of plain numbers: the formula becomes

If you want, you can simplify it by expanding the square and then multiply the two parenthesis:

Nice
area=pir^2
the areas are
pir^2+pi(2r)^2
they add to 8pi
8pi=pir^2+pi(2r)^2
undistribute pi
8pi=pi(r^2+(2r)^2)
divide both sides by pi
8=r^2+(2r)^2
expand
8=r^2+4r^2
add
8=5r^2
divide by 5
8/5=r^2
sqrt both sides
√(8/5)=r
double since it is double
2√(8/5) is radius of bigger aka (4√10)/5
radius=(4√10)/5
Answer:
A) 370
Explanation:
(5*180)/7=900/7=128.5714285714286
The angle is approximately 129 degrees.
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The answer is, 25z^4+30z^3+29z^2+12z+4
Or z(z(z(25z+30)+29)+12)+4