## Calculus 8th Edition

Use law of cosines, we have $c^{2}=a^{2}+b^{2}-2ab cos \theta$ As per question: $|AB|^{2}=|AC|^{2}+|BC|^{2}-2|AC||BC| cos 103^{\circ}$ $|AB|^{2}=820^{2}+910^{2}-2(820)(910) cos 103^{\circ}$ $|AB|=\sqrt {820^{2}+910^{2}-2(820)(910) cos 103^{\circ}}$ $|AB|=1355$ m