To find conjecture about regular polygon, use the formula 
Where, n = number of sides of the regular polygone
1) Triangle
n =3
So, Conjecture of the triangle =
= 120
2) Square
n =4
So, Conjecture of the square =
= 90
3) Pentagone
n = 5
So, Conjecture of the pentagon =
= 72
4) Hexagone
n = 6
So, Conjecture of the pentagon =
= 60.
Where, n = number of sides of the regular polygone
1) Triangle
n =3
So, Conjecture of the triangle =
2) Square
n =4
So, Conjecture of the square =
3) Pentagone
n = 5
So, Conjecture of the pentagon =
4) Hexagone
n = 6
So, Conjecture of the pentagon =