Elementary Geometry for College Students (6th Edition)

$α = 90^{\circ}$
1. Use the Law of Cosines to find $α$ $c^{2} = a^{2} + b^{2} - 2abcos(C)$ $(26)^{2} = (24)^{2} + (10)^{2} - 2(24)(10)cos(α)$ $676 = 576 + 100 - 480cos(α)$ $676 = 676 - 480cos(α)$ $0 = - 480cos(α)$ $cos(α) = 0$ $α = 90^{\circ}$