Statement-I     If the interior angle of a regular polygon is $60°$ , then it has $\text{3}$ sides.

Statement-II     If the interior and exterior angles of a regular polygon are equal, then it is a pentagon

I) The interior angle of a regular polygon is $\frac{(n-2)\times 180°}{n}$       $(\therefore$ n is number of sides of regular polygon $)$

$\frac{(n-2)\times 180°}{n}=60°$

$(n-2)\times \stackrel{3}{\cancel{180}}=\stackrel{1}{\cancel{60}}n$

$(n-2)\times 3=n$

$3n-6=n$

$3n-n=6$

$2n=6$

$n=3$

$\therefore$  The number of sides of a regular polygon is 3.

II) The interior and exterior angles of a regular polygon are equal.

$\frac{(n-2)\times 180}{n}=\frac{360}{n}$  

$\frac{(n-2)\times \stackrel{1}{\cancel{180}}}{\cancel{n}}=\frac{\stackrel{2}{\cancel{360}}}{\cancel{n}}$

$n-2=2$

$n=2+2$

$n=4$

The number of sides of a regular polygon = 4.

If the interior and exterior angles of a regular polygon are equal, then regular polygon  is a quadrilateral.