Dkumpulin bsok saybantuin dong pliss..no 4 sma no 2

tan (a -b) = (tan a - tan b)/ 1 + tan a.tan b
( tan 60 - tan 30 )/ 1 + tan 60. tan 30)
= tan (60-30)
= tan 30
= (1/3)akar 3
cosec 30. cos 60 + cos 90.sin90
1/sin 30.cos 60 + 0.1
= 1/(1/2).1/2 +0
= 2.1/2
= 1