Answer:

Hope's it helps

1. For TRIANGLE

We know perimeter of a triangle is the total length (distance) of the boundary of a triangle. Perimeter of a triangle is the sum of lengths of its three sides. = 2 cm + 4 cm + 3 cm, (add the length of each side of the triangle).

2. For SQUARE

Perimeter of a square is 4 times of s side. Perimeter of a square = 4 × length of a side. 1. Each side of a square is 2.5 cm

3 For RECTANGLE

a rectangle we know that two opposite sides are equal. So, PQ = SR and PS = QR

If PS = l and PQ = b

Perimeter of a Rectangle

2Save

Perimeter of the rectangle = PQ + QR + RS + SP

= b +l + b + l

= 2b +2l

Again,

ABCD is a rectangle. We know that the opposite sides of a rectangle are equal.

Perimeter of a Rectangle

AB = CD = 5 cm and BC = AD = 3 cm

So, the perimeter of the rectangle ABCD = AB + BC + CD + AD = 5 cm + 3 cm + 5 cm + 3 cm = 16 cm

It can be written as 5 cm + 5 cm + 3 cm + 3 cm

= (2 × 5) cm + (2 × 3) cm

= 2 (5 + 3) cm

= 2 × 8 cm

= 16 cm

4. For Octagon

Perimeter of Regular Octagon is equal to eight times the length its side.

In other words, the sides of a regular octagon are congruent. Each of the interior angle and the exterior angle measure 135° and 45° respectively, in a regular octagon.

...

Octagon Formulas.

Formulas for Octagon

Area of an Octagon 2a2(1+√2)

Perimeter of an Octagon 8a

Hope it helps