cos 60° = 1/2 ⇒ cos² 60° = 1/4

sin 45° = 1/√2 ⇒ sin² 45° = 1/2

sin 30° = 1/2 ⇒ sin² 30° = 1/4

cos 90° = 0 ⇒ cos² 90° = 0

∴ 2 cos²60° + 3 sin²45° — 3 sin²30° + 2 cos²90°

= 2(1/4) + 3(1/2) – 3(1/4) + 2(0)

= (1/2) + (3/2) – (3/4) = 2 – (3/4)

= 5/4