Let a, b, c be the lengths of sides of the base and h be the height of the prism.
Total surface area
= \(2\left(\sqrt{\dfrac{a+b+c}{2}\left(\dfrac{b+c-a}{2}\right)\left(\dfrac{a-b+c}{2}\right)\left(\dfrac{a+b-c}{2}\right)}\right)+h(a+b+c)\)
Sorry for being too scary, but that formula is real XDDDD
Simpler version:
Total surface area
= \(2(\text{base area})+h\times(\text{perimeter})\)
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