Chapter 13, Trigonometric Ratios and Functions - 13.6 Apply the Law of Cosines - 13.6 Exercises - Skill Practice - Page 892: 23

$$A=14\sqrt{6270}$$

By Heron's Formula, we know: $$A=\sqrt{s(s-a)(s-b)(s-c)}$$ Where: $$s=\frac{a+b+c}{2}$$ Thus, we find: $$s=\frac{47+49+58}{2}=77 \\ A=\sqrt{77\left(77-47\right)\left(77-49\right)\left(77-58\right)} \\ A=14\sqrt{6270}$$