Answer:
C
Step-by-step explanation:
The formula for the area of a trapezoid is: (height)(sum of parallel lines)
Thus, the formula in this question would be: (4)(4+8) which is option C
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