Using Cos formula of a triangle
let BA be x
x² = a² + b² -2abCos(90°)
x² = 64 + 196
x = √260
To find <B using Cos again
b² = a² + c² - 2acCos(B)
196 = 64 + 260 - 2 * 8 * √260 * cosB
196=324 - 16√260 *cosB
324-196=16√260CosB
8 = √260CosB
CosB = 8/√260
B = cos-¹(8/(√260))
I don't have a calculator so complete it by yourself, the calculation aspect.