What is the angle between a=⟨1,1⟩\mathbf{a} = \langle 1, 1 \ranglea=⟨1,1⟩ and b=⟨1,0⟩\mathbf{b} = \langle 1, 0 \rangleb=⟨1,0⟩?
0∘0^{\circ}0∘
30∘30^{\circ}30∘
45∘45^{\circ}45∘
90∘90^{\circ}90∘