Answer:
Step-by-step explanation:
a = 9 mm ; b = 6 mm ; c = 12 mm
S = (a + b +c) / 2
[tex]= \dfrac{9 + 6 + 12}{2}\\\\= \dfrac{27}{2}\\\\= 13.5 \ mm[/tex]
S - a = 13.5 - 9 = 4.5 mm
s -b = 13.5 - 6 = 7.5 mm
s -c = 13.5 - 12 = 1.5 mm
Area = [tex]\sqrt{s(s-a)(s-b)(s-c)}[/tex]
[tex]= \sqrt{13.5 * 4.5 * 7.5 * 1.5} \\\\= \sqrt{683.4375} \\\\=26.1 \ mm^{2}[/tex]
