The area of a regular octagon is 35 cm2 What is the area of

The area of a regular octagon is 35 cm². What is the area of a regular octagon with sides five times as long?

A. 625 cm²

B. 875 cm²

C. 175 cm²

D. 245 cm²

Solution

As we know that

area of  a regular octagon is =2(1+2)a² = 35

where a is side of regular octagon
a = root ( 35 / 2(1+2))

Now area of a regular octagon with sides 5 times as long = 5a

and New area = 2(1+2) (5* root ( 35 / 2(1+2)) )²

   ⁼ 2(1+2)  ((25* 35) / 2(1+2))

=875 cm²

Answer: A : 875 cm² is correct