Perimeter of Triangles [pptime time="0:55"](0:55) [/pptime]

Generally, we find the perimeter of a triangle by adding the lengths of all three sides. 🌟 Perimeter of an Isosceles Triangle: An isosceles triangle has two equal sides ($a$) and one different side ($b$). The formula is: $$P = 2a + b$$ For example, if a triangle has two equal sides of 5 cm and a third side of 3 cm, find its perimeter: $$ \begin{align} P &= (2 \times a) + b \\[0.5em] &= (2 \times 5\,\text{cm}) + 3\,\text{cm} \\[0.5em] &= 10\,\text{cm} + 3\,\text{cm} \\[0.5em] &= 13\,\text{cm} \end{align} $$ 🌟 Perimeter of an Equilateral Triangle An equilateral triangle has all three sides the same length ($a$). The formula is: $$P = 3a$$ For example, if all sides of a triangle are 7 cm, find its perimeter: $$ \begin{align} P &= 3 \times a \\[0.5em] &= 3 \times 7\,\text{cm} \\[0.5em] &= 21\,\text{cm} \end{align} $$

Perimeter of a Polygon - Rectangles, Triangles, and Compound Shapes

Perimeter of a Polygon

🎬 Video: How to Calculate Perimeter of Shapes

What is the Perimeter of a Polygon? (0:01)

What is a Polygon?

A polygon is any flat shape with straight sides, like triangles, rectangles, squares, or pentagons.

What is the Perimeter?

The perimeter is the total distance all the way around a shape.

How to Find the Perimeter of a Polygon?

To find the perimeter of a polygon, add up the lengths of all the sides.

How to Find the Perimeter of a Rectangle? (0:12)

🌟 Perimeter of a Rectangle Formula:

$$P = 2 \times (l + w)$$

where $l$ is the length and $w$ is the width.

🔎 Perimeter of a Rectangle Example:

For a rectangle with 5 cm length and 3 cm width, find its area.

$$
\begin{align}
P &= 2 \times (5\,\text{cm} + 3\,\text{cm}) \\[0.5em]
&= 2 \times 8\,\text{cm} \\[0.5em]
&= 16\,\text{cm}
\end{align}
$$

Finding the Perimeter of a Square (0:35)

🌟 Perimeter of a Square Formula:

$\times s$$$

where $s$ is the length of any side.

🔎 Perimeter of a Square Example:

For a square with side length 2 m, find its perimeter.

$$
\begin{align}
P &= 4 \times 2\,\text{m} \\[0.5em]
&= 8\,\text{m}
\end{align}
$$

Perimeter of Triangles (0:55)

Generally, we find the perimeter of a triangle by adding the lengths of all three sides.

🌟 Perimeter of an Isosceles Triangle:

An isosceles triangle has two equal sides ($a$) and one different side ($b$).

The formula is: $$P = 2a + b$$

For example, if a triangle has two equal sides of 5 cm and a third side of 3 cm, find its perimeter:

$$
\begin{align}
P &= (2 \times a) + b \\[0.5em]
&= (2 \times 5\,\text{cm}) + 3\,\text{cm} \\[0.5em]
&= 10\,\text{cm} + 3\,\text{cm} \\[0.5em]
&= 13\,\text{cm}
\end{align}
$$