find the value of cos^267 - sin^223

Please find below the solution to the asked query:

We have :  Cos² 67$°$ - Sin² 23$°$ , So

= Cos² 67$°$ - Sin² ( 90$°$ - 67$°$ ) ,

= Cos² 67$°$ - Cos² 67$°$ ,                                 [ We know : Sin ( 90$°$ - a ) = Cos a ]

= 0                                                                   ( Ans )

Hope this information will clear your doubts about topic.