Answer:
 dA/dt = 0.375â3 ft² â 0.6495 ft²/s
Step-by-step explanation:
The area is given by the formula ...
 A = (1/2)ab¡sin(C)
where a and b are side lengths, and C is the angle between them. Differentiating, we have ...
 dA/dt = (1/2)ab¡cos(C)¡dC/dt
Filling in the given information, we get ...
 dA/dt = (1/2)(3 ft)(5 ft)(cos(Ď/6))(0.1 rad/s) = 0.75(â3)/2 ft²/s
 dA/dt = 0.375â3 ft² â 0.6495 ft²/s