Find expert advice and community support for all your questions on IDNLearn.com. Get accurate answers to your questions from our community of experts who are always ready to provide timely and relevant solutions.

Question 18 (5 points)

A regular pentagon's sides each have a length of 7 cm and an apothem of 8 cm.

What is the area of the pentagon?

A. 150 cm²
B. 146 cm²
C. 127 cm²


Sagot :

To find the area of a regular pentagon, where each side has a length of 7 cm, and the apothem is 8 cm, we can use the following steps:

1. Calculate the Perimeter:
- A regular pentagon has 5 sides.
- Each side has a length of 7 cm.
- Therefore, the perimeter (P) of the pentagon can be calculated as:
[tex]\[ P = \text{number of sides} \times \text{side length} = 5 \times 7 = 35 \text{ cm} \][/tex]

2. Calculate the Area:
- The formula to find the area (A) of a regular polygon using the apothem (a) and perimeter is:
[tex]\[ A = \frac{1}{2} \times \text{perimeter} \times \text{apothem} \][/tex]
- Substitute the values of the perimeter (35 cm) and the apothem (8 cm):
[tex]\[ A = \frac{1}{2} \times 35 \times 8 = \frac{1}{2} \times 280 = 140 \text{ cm}^2 \][/tex]

Thus, the area of the pentagon is 140 cm². None of the listed options match this answer exactly, so it seems there might have been an error in the provided options. However, based on our calculations, 140 cm² is the correct area of the pentagon.