Question 1062168
For the base, I get:  
    {{{ h = sqrt(12.9^2 - 6.45^2) = 11.17173 }}}
    {{{ A_base = (1/2)(h)(b) = (1/2)(11.17173)(12.9) = 72.0576 }}}  sq in

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For the sides:

 Each face {{{ A_face = (1/2)(7.2)(12.9) = 46.44 }}} sq in

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Total Area = 3*A_face + A_base
                     3*(46.44) + 72.0576  = 139.22 + 72.0576 = 211.3776 sq in


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My answer agrees with your textbook.   The problem appears to be in your calculation of the area of the base.   I recommend drawing the base (equilateral triangle) and figure the height yourself.  The number 5.6cm may just be a distractor thrown in, I didn't use it.