Answer:
Step-by-step explanation:
First, you have to use the law of cosines which is c² = a² + b² - 2abcosФ where Ф is the angle measure between sides a and b. So, just plug-in a = 10, b = 12, and Ф = 72 into the equation and you will get (I won't show all the calculations):
c = 13.0321
Then plug that into the area formula to get:
(0.5)(10)(12)(0.225496911)
Which is about:
13.53
