Answer
$70.4 m^2$
Work Step by Step
The area will be equal to half the product of the adjacent sides and the sine of the angle between them.
Therefore, we have
$Area=\dfrac{1}{2}(12)(12)\sin 78^{\circ}$
or, $Area=\dfrac{1}{2}(12)(12)(0.978)=70.4 m^2$
