Answer
β = 90°
Work Step by Step
using theorem 11.4.3 Law of cosine
a=6,b =10, c=8
$b^{2}$ = $a^{2}$ + $c^{2}$ - 2ac cos β
$10^{2}$ = $(6)^{2}$ + $(8)^{2}$ - 2*6*8*cos β
100 = 36+64 - 96cos β
96cos β = 36 +64 -100
96cos β = 0
cos β = 0
β = $cos^{-1}$(0)
β = 90°
