Given
 Area of the regular pentagon is 6.9 cm².
Find out the perimeter of a regular pentagon
To proof
Formula
Area of regular pentagon is

As given in the question 
area of regular pentagon = 6.9 cm²
now equating the area value with the area formula.

Now put 
√5 = 2.24 ( approx)
put in the above equation

thus
a² = 4.01 
a = √ 4.01
a = 2.0 cm ( approx)
As perimeter  represented the sum of all sides.
i.e regular pentagon have five sides of equal length.
Thus 
perimeter of the regular pentagon = 5 × side length
                                                          = 5 ×2.00
therefore the perimeter of the regular pentagon = 10cm
option c is correct 
Hence proved
 
        
                    
             
        
        
        
Answer:
-3,5
Step-by-step explanation:







Or


 
        
             
        
        
        
12-15=3 ............................................................
        
             
        
        
        
For given problem:
Put midpoint of ellipse, (0,0) at epicenter of bridge at
ground level.
Specified length of vertical major axis = 70=2a
a=35
a^2=1225
 
Equation of ellipse:
 
x^2/b^2+y^2=1
 
plug in coordinates of given point on ellipse(25, 10)
 
25^2/b^2 + 10^2/a^2 = 1
 
625/b^2 + 100/1225=1
 
625/b^2 = 1 - 100/ 1225 = .918
 
b^2 = 625/.918 ≈ 681
 
b ≈ 26.09
 
length of minor axis = 2b = 2(26.09) ≈ 52.16 ft
 
Span of bridge ≈ 52.16 ft
 
        
             
        
        
        
3 to the -2 power is basically 3x-3, which is -9, and -5 to the -3 power is (-5)(-5)(-5) which is equal to -125. hope that helped you out, bud!