Nilai cos60.cos30-sin60.sin30

cos 60 . cos 30 - sin 60 . sin 30
= 1/2 . 1/2 akar3 - 1/2 akar3 . 1/2
= 1/4 akar3 - 1/4 akar 3
= 0

Ingat bentuk cos (a + b) = cos a.cos b - sin a.sin b
cos 60.cos 30 - sin 60.sin 30
= cos (60 + 30) = cos 90 = 0