Odpowiedź :
1. B) 150°
f=2%5E2%20%3D%20(2%5Csqrt2)%5E2%20%2B%20(%5Csqrt2%20%2B%20%5Csqrt6)%5E2%20-%202%20%5Ccdot%202%5Csqrt2%20%5Ccdot%20(%5Csqrt2%20%2B%20%5Csqrt6)%20%5Ccos%20%5Calpha%5C%5C4%3D8%2B2%2B6%2B2%20%5Csqrt%7B12%7D%20-%208(1%2B%5Csqrt3)%20%5Ccos%20%5Calpha%5C%5C-12%20-4%20%5Csqrt3%20%3D%20-8(1%2B%5Csqrt3)%20%5Ccos%20%5Calpha%5C%5C%5Ccos%20%5Calpha%20%3D%20%5Cfrac%7B3%2B%5Csqrt3%7D%7B2(1%2B%5Csqrt3)%7D%5C%5C%5Ccos%20%5Calpha%20%3D%20%5Cfrac%7B%5Csqrt3%7D%7B2%7D%5C%5C%5Calpha%20%3D%2030%5E%5Ccirc
2. f=e%5E2%20%3D%204%5E2%20%2B%20(2%2B2%5Csqrt3)%5E2%20-%202%20%5Ccdot%204%20%5Ccdot%20(2%2B2%5Csqrt3)%20%5Ccos%20150%5E%5Ccirc%5C%5Ce%5E2%20%3D%2016%20%2B%204(1%2B%5Csqrt3)%5E2%20-%2016%20(1%2B%5Csqrt3)%20%5Ccdot%20(-%5Cfrac%7B%5Csqrt3%7D%7B2%7D)%5C%5Ce%5E2%20%3D%2016%20%2B%204%2B12%2B8%5Csqrt3%20%2B%208%5Csqrt3%20%2B%2024%5C%5Ce%5E2%20%3D%2056%20%2B%2016%20%5Csqrt3%5C%5Ce%20%3D%20%5Csqrt%7B56%20%2B%2016%20%5Csqrt3%7D
f=f%5E2%20%3D%204%5E2%20%2B%20(2%2B2%5Csqrt3)%5E2%20-%202%20%5Ccdot%204%20%5Ccdot%20(2%2B2%5Csqrt3)%20%5Ccos%2030%5E%5Ccirc%5C%5Cf%5E2%20%3D%2016%20%2B%204(1%2B%5Csqrt3)%5E2%20-%2016%20(1%2B%5Csqrt3)%20%5Ccdot%20(-%5Cfrac%7B%5Csqrt3%7D%7B2%7D)%5C%5Cf%5E2%20%3D%2016%20%2B%204%2B12%2B8%5Csqrt3%20-8%5Csqrt3%20-24%5C%5Cf%5E2%20%3D%208%5C%5Cf%3D%202%5Csqrt2
ODP: C)