We can calculate using cosinus method in triangle c² = a² + b² - 2ab cos c
Plug in the number to the formula c² = a² + b² - 2ab cos c c² = 10² + 8² - 2(10)(8) cos 105° c² = 100 + 64 - 160 cos 105° c² = 164 - 160 (-0.26) c² = 164 + 41.6 c² = 205.6 c = √205.6 c =14.34
