Evaluate :

Expanding along the first row

⇒ |A| = 0(0 – sinβ(–sinβ) ) –sinα(–sinα× 0 – sinβ cosα ) – cosα((–sinα)(–sinβ) – 0× cosα )

|A| = 0 + sinα sinβ cosα – cosα sinα sinβ

|A| = 0