[" 4."sin57^(@)cos27^(@)-cos37^(@)32^(@)=(1)/(2)],[" 5."sin20^(@)28'cos9^(@)32'+cos20^(@)28'sin9^(@)32'=]

cos57^(@)+sin27^(@)=

cos9^(@)-sin9^(@)=

(2cos40^(@)-cos20^(@))/(sin20^(@))

(2cos40^(@)-cos20^(@))/(sin20^(@))

(2cos40^(@)-cos20^(@))/(sin20^(@))=?

Prove that (i) sin 70^(@) cos 10^(@) -cos 70^(@) sin 10^(@) =(sqrt(3))/(2) (ii) cos 50^(@) cos 10^(@) -sin 50^(@) sin 10^(@) =(1)/(2) (ii) cos 80^(@) cos 20^(@) + sin 80^(@) sin 20^(@) =(1)/(2) (iv) sin 36^(@) cos 9^(@) + cos 36^(@) sin 9^(@) =(1)/(sqrt(3))

Prove that (sin32^(@)cos58^(@)+cos32^(@)sin58^(@))=1.

(cos 28^(@))/(sin 62^@)=?

(cos9^@+sin9^@)/(cos9^@-sin9^@)=

(cos9^(@)+sin9^(@))/(cos9^(@)-sin9^(@))=?