25cm x 4 sides = 100 cm perimeter
A triangle with side a: 40, side b: 25, and side c: 25cm has an area of 300cm2
Regular = all sides equal so all sides of 25 cm. Decagon = 10 sides. So perimeter = 10*25cm = 250 cm.
The perimeter is 20 cm
Then the square will have 4 equal sides of 5cm with a perimeter of 20cm and an area of 25 square cm
If you are talking about a rectangle, then it is 90 cm.
P = 20cm
A pentagon has 5 sides. A regular pentagon has sides of all the same length. So a regular pentagon of side 5cm has a perimeter of 5 x 5cm = 25cm.
Any shape at all can have any perimeter at all.
Yes, it definately can and always will be. Since you wrote that both pentagons are regular, all sides (and angles) are equivalent to each other. On the first pentagon, one side measured 5cm, so therefore the rest of the sides total up to 25cm. Since the second pentagon has perimeter 25cm, the pentagons must be congruent.