Answer:
Step-by-step explanation:
[tex]R =\dfrac{1}{2}abSin \ C\\\\\\= \dfrac{1}{2}*12.1*13.8*Sin \ 71 \\\\\\= \dfrac{1}{2}*12.1 *13.8 * 0.95\\\\= 79.3 \ ft^{2}[/tex]
