Given:
The base of the triangle = 5 mm
The other side of the of the triangle = 9 mm
The 3rd side of the triangle = 9 mm
The height of the triangle = 7 mm
The height of the prism = 12 mm
To find the surface area of the the prism.
Formula:
The surface area of a triangular prism is
![SA = bh+(s_{1} +s_{2} +s_{3})H](https://tex.z-dn.net/?f=SA%20%3D%20bh%2B%28s_%7B1%7D%20%2Bs_%7B2%7D%20%2Bs_%7B3%7D%29H)
Where,
h be the height of the triangle
H be the side of the prism
b be the base of the triangle
are the sides of the triangle.
Now,
Putting, b=5, H= 12, h=7,
we get,
![SA = (5)(7)+(5+9+9)(12)](https://tex.z-dn.net/?f=SA%20%3D%20%285%29%287%29%2B%285%2B9%2B9%29%2812%29)
or, ![SA = 35+276](https://tex.z-dn.net/?f=SA%20%3D%2035%2B276)
or,
sq mm
Hence,
The surface area of the triangular prism is 311 sq mm.