If cos(A)=17\cos(A) = \frac{1}{7}cos(A)=71 and cos(B)=1314\cos(B) = \frac{13}{14}cos(B)=1413, find the angle A−BA-BA−B.
30∘30^\circ30∘
45∘45^\circ45∘
60∘60^\circ60∘
90∘90^\circ90∘