I think its 81 degrees
hope this helps :)
A. The answer is 494.6 rounded.
b. She most likely did not add 417.62 to 76.9
To ease your problem, consider "L" as you x-axis
Then the coordinate become:
A(- 4 , 3) and B(1 , 2) [you notice that just the y's changed]
This is a reflection problem.
Reflect point B across the river line "L" to get B', symmetric of B about L.
The coordinates of B'(1 , -1) [remember L is our new x-axis]
JOIN A to B' . AB' intersect L, say in H
We have to find the shortest way such that AH + HB = shortest.
But HB = HB' (symmetry about L) , then I can write instead of
AH + HB →→ AH + HB'. This is the shortest since the shortest distance between 2 points is the straight line and H is the point requiered
![\left[\begin{array}{ccc}2&6&3\\-5&1&4\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D2%266%263%5C%5C-5%261%264%5Cend%7Barray%7D%5Cright%5D)
R1 ÷ 2 = ![\left[\begin{array}{ccc}1&3&1.5\\-5&1&4\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C-5%261%264%5Cend%7Barray%7D%5Cright%5D)
R2 ÷ -5 = ![\left[\begin{array}{ccc}1&3&1.5\\1&-0.2&-0.8\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C1%26-0.2%26-0.8%5Cend%7Barray%7D%5Cright%5D)
R2: R1 - R2 = ![\left[\begin{array}{ccc}1&3&1.5\\0&3.2&2.3\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C0%263.2%262.3%5Cend%7Barray%7D%5Cright%5D)
R2 ÷ 3.2 = ![\left[\begin{array}{ccc}1&3&1.5\\0&1&0.71875\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%261.5%5C%5C0%261%260.71875%5Cend%7Barray%7D%5Cright%5D)
R1: R1 - 3R2 = ![\left[\begin{array}{ccc}1&0&0.65625\\0&1&0.71875\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%260%260.65625%5C%5C0%261%260.71875%5Cend%7Barray%7D%5Cright%5D)
Answer: x = 0.65625, y = 0.71875
