Question 515082
{{{ area = (1/2)*b*h }}}
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I assume you mean the area is:  {{{ 24 cm^2 }}}
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{{{ ht = 3 cm }}}
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{{{ (1/2)*b*3 = 24 }}}
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{{{ 3b = 48 }}}
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{{{ b = 16 cm }}}
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Done.