To convert an angle from degrees to radians, multiply by π/180°.
Your angle is
(-280°)*(π/180°) = -14π/9
The appropriate choice is ...
B) (-14π/9)
Two solutions:
1. x =(100-√2160)/2=50-6√ 15 = 26.762
2. x =(100+√2160)/2=50+6√ 15 = 73.238
It is verg important because once diving "The length of one cathetus in a right triangle with equal catheti is the squareroot of half of the squared hypotenuse. And yeah