Perimeter = Sum of all side lengths

Perimeter of a rectangle = 2 × length + 2 × breadth

P = 2(1 + b) ⇒ (i) l = `P/2` − b, i.e., length = `"Perimeter"/2` − breadth

                         (ii) l = `P/2` − l, i.e., breadth = `"Perimeter"/2` − length

Perimeter of Square = Total boundary of the square

                                   = Side + Side + Side + Side

P = 4 × Side

Or: P = 4s (where 's' represents the side length)

side = ` "perimeter"/"4"`

Always include the correct linear unit (cm, m, mm, km, etc.)

Perimeter of a Triangle = 3 × length of a side.

For an equilateral triangle with side length = s

P = s + s + s

   = 3 × s

Perimeter = 3 × Length of one side

Area =  Amount of space inside a flat shape

Area of triangle = `(1/2) × "base" × "height" = 1/2 × b × h`.