How do you solve the perimeter of 20m to 9m?

Answer 1

Assuming the figure is a plane regular rectangle.

Then there are two sides of 20m and two sides of 9m .

We could then write 20 + 20 + 9 + 9 = 58m

However we can alter this to (2 x 20) + ( 2 x 9) = 40 + 18 = 58m

or we could say 2*(20 + 9) = 2(29) = 58m.

However, you only mention two sides. you must specify the shape of the figure, be it a triangle, rectangle, kite. Trapezium and Square are discounted because a trapezium may have difference lengths ( an asymmetric trapezium), and a square has has four sides all the same length.

Then again the polygon might be of irregular shape( four different lengths).

Answer 2

You need to know what the shape is before you can even think about trying to calculate its perimeter.