The area of a regular octagon is 25. What is the area of a regular octagon with sides five times as large as the sides of the first octagon?

Answer 1

Area of octagon:

A=2*[1+sqroot(2)]*a^2

A1=Area of first octagon

A1=25

A2=Area of five time lager side octagon

A1=2*[1+sqroot(2)]*a^2

A2=2*[1+sqroot(2)]*(5a)^2

A2=2*[1+sqroot(2)]*25*a^2

A2/A1=2*[1+sqroot(2)]*25*a^2/2*[1+sqroot(2)]*a^2= 25

A2/A1=25

A2=25*A1= 25*25= 625

Answer 2

In google type:
Octagon

When you see list of results click on wikipedia