Answer:
8.2500000000 miles
Explanation:
I drew a triangle to illustrate the reference triangle.
So, Amy ran from summit A for 3 miles then turned to her right by 50 degrees (creating angle B of 130 degrees), and runs for another 6 miles.
Based on the Cosines Law, we have:
![cos(B) = (c^(2) + a^(2) - b^(2) )/(2 * c * a)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wa8swki7yjrgywyry7dyl83w132qug108z.png)
If we isolate b, we have the following formula.
![b = \sqrt{a^(2) + c^(2) - 2 * a * c * cos(B) } \\ \\b = \sqrt{6^(2) + 3^(2) - 2 * 6 * 3 * cos(130) } = 8.25](https://img.qammunity.org/2020/formulas/mathematics/middle-school/lobgrj10vdzjek5rkcjo16qtrcvbjcvflp.png)
So, as she stops at summit C, she's 8.25 miles away from her starting point.