A triangular plot of land has sides that measure 5 meters, 7 meters,and 10 meters. What is the area of this plot of land, to thenearest tenth of a square meter?
Many ways of doing it. Here're two:
1. Heron's Formula: Heron's formula - Wikipedia, the free encyclopedia
2. Use the cosine rule to get an angle. Then use the area formula Area $\displaystyle = \frac{1}{2} a b \sin C$.