Expanding along the second row⇒ |A| = sinβ (cosα×cosα sinβ + sinα × sinα sinβ) + cosβ (cosα cosβ × cosα + sinα×sinα cosβ) – 0|A| = sin2 β (cos2α + sin2α) + cos2β (cos2α + sin2α)|A| = sin2 β (1) + cos2β (1)|A| = sin2 β + cos2β|A| = 1