Question

Area of triangle formula root under s(s-a)(s-b)(s-c)

Answer 1

yes, this formula is correct

Answer 2

$s = \frac{1}{2} (perimeter \:of \:triangle ) \\ s = \frac{a + b + c}{2} \\ area \: = \sqrt{s(s - a)s(s - b)s(s - c)}$
hope you understand it