To find out a glass prism's surface are you should first find the, base's are. Since the base is triangle, it's are formula is : [tex]A\quad =\quad \frac { h.b }{ 2 } [/tex] (which h is height and b is base length). [tex]A\quad =\quad \frac { 7,8.9 }{ 2 } \\ A=\quad \frac { 70,2 }{ 2 } \\ A=\quad 35,1[/tex] since there are two triangle's their total area will be 70.2 To find the remaining surface's are multiply the perimeter of the base with the length. [tex]perimeter\quad =\quad 9\cdot 3=27\\ 27\cdot 75=2025[/tex] then sum the total surface : 70,2 + 2025 = 2095,2
