Perimeter is the total length of all sides of a geometric figure, typically denoted by the symbol P. Children first encounter this concept in primary school, but formulas for complex figures are studied until the end of school. Online math tutors at Mathema have compiled the basic formulas for determining the perimeters of squares, rectangles, triangles, circles, rhombuses, and other geometric figures.
What is perimeter?
Perimeter is the length of all sides of a figure. It is often needed in mathematics to find other properties of geometric figures. For example, to find the area of a triangle, you can use half of its perimeter. In real life, perimeter is used in architecture, agriculture, and various industries. This is one of the basic concepts of geometry.
How to find the perimeter of a rectangle? In a rectangle, two parallel sides have the same length. Therefore, to find the perimeter of a rectangle, you need to add the two sides that form a right angle and multiply the result by two.
𝑃=2(𝑎+𝑏) where a and b are the adjacent sides of the rectangle.
How to find the perimeter of a triangle?
To find the perimeter of a triangle, you need to add all its sides. There is no special formula for this figure. If the triangle is equilateral, you can multiply the length of its side by three.
𝑃=𝑎+𝑏+𝑐 𝑃=3𝑑 where a, b, and c are the sides of the triangle, and d is the side of an equilateral triangle.
How to find the perimeter of a square?
A square is a rectangle whose four sides are equal. Therefore, to find its perimeter, you need to multiply the length of one side by four. You can also find the perimeter of a square if you know the length of its diagonal.
𝑃=4𝑎 𝑃=2√2𝑑 where a is the side of the square and d is the diagonal of the square.
How to find the perimeter of a parallelogram?
A parallelogram has similar properties to a rectangle, as its parallel sides are also equal. Therefore, the perimeter of a parallelogram is also equal to the sum of adjacent sides multiplied by two.
𝑃=2(𝑎+𝑏) where a and b are the adjacent sides of the parallelogram.
How to find the perimeter of a rhombus?
A rhombus is a parallelogram with all sides equal. This property makes it similar to a rectangle, so the perimeter of a rhombus can also be calculated by multiplying one side by four.
𝑃=4𝑎 where a is the side of the rhombus.
How to find the perimeter of a circle?
The perimeter of a circle, or its circumference, is found using the number Pi. To find the perimeter of a circle, you need to know its diameter or radius.
𝑃=2𝜋𝑟 𝑃=𝜋𝑑 where r is the radius of the circle, d is the diameter of the circle, and π is Pi (approximately 3.14).
