Here is your answer
Given area is
z^2 + 18z + 81
= z^2 + 2× z × 9 + 9^2
[using (a+b)^2= a^2 + 2ab + b^2], we get
= (z+9)^2
we know that area of a square is represented by side^2.
So, here
Side of square is

HOPE IT IS USEFUL
Pentagon has 5 angles. 360/5= 72 degrees
16-gon has 16 angles. 360/16= 22.5 degrees
dodecagon has 12 angles. 360/12= 30 degrees
The measure of the exterior angle of any regular polygon is 360 divides by the number of sides the polygon has.
The answer is;
Flame test is a qualitative test".
Flame test is performed for detecting metals in a compound and metals are detected by the color of the flame, and flame color identifies that which metal is this. so this is a qualitative test, different types of metals shows different color of flames.