`a)A= tan 76^0 -cot 14^0`

     `=cot (90^0 -76^0)-cot14^0`

     `=cot 14^0 - cot 14^0=0`

`b) B=Sin 33^0 -cos 57^0`

      `=cos (90^0 -33^0) - cos 57^0`

      `=cos 57^0 -cos 57^0 =0`

`c) C=sin 30^0 +cos 30^0=1/2 + (\sqrt3)/2 =(1+\sqrt3)/2`

`d) D=sin 30^0 +sin 60^0=1/2 + (\sqrt3)/2=(1+\sqrt3)/2`

`e) E=tan 30^0 + cot 60^0=(\sqrt3)/3 + (\sqrt3)/3 =2/3 \sqrt3`

`f) F=2 tan 45^0 - cot 60^0 =2.1- (\sqrt3)/3=(6-\sqrt3)/3`

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Các TH đặt biệt bắt gặp trên:
`sin 30^0 =1/2 =cos 60^0`

`sin 60^0 =(\sqrt3)/2 = cos 30^0`

`tan 45^0 =1`

`tan 30^0 = (\sqrt3)/3 =cot 60^0`