In Exercises 25–30, use Heron's formula to find the area of each triangle. Round to the nearest square unit.

a = 11 yards, b = 9 yards, c = 7 yards

In Exercises 35–36, the three given points are the vertices of a triangle. Solve each triangle, rounding lengths of sides to the nearest tenth and angle measures to the nearest degree.

A(0, 0), B(-3, 4), C(3, -1)

A surveyor wishes to find the distance across a river while standing on a small island. If she measures distances of $a=30m$ to one shore, $c=60m$ to the opposite shore, and an angle of $B=100\(\degree\)$ between the two shores, find the distance between the two shores.

Use the Law of Cosines to find the angle $C$, rounded to the nearest tenth.

Solve the triangle: $a=5$, $b=15$, $c=13$.

Solve each triangle. See Examples 2 and 3.

a = 3.0 ft, b = 5.0 ft, c = 6.0 ft