Grade 11TrigonometryPlxxxx see this image,,.....que 9 and 10.....fast.... Tanisha 6 Years agoGrade 11
ArunApproved Tutor Answer6 Years agoDear student please ask only one question in one thread.9. Cos^2α+cos^2(α+β)-2cosαcosβcos(α+β)=cos^2α+cos^2(α+β)-{cos(α+β)+cos(α-β) }cos(α+β)=cos^2α+cos^2(α+β)-{cos^2(α+β)+cos(α-β)*cos(α+β)}=cos^2α+cos^2(α+β)-cos^2(α+β)-cos(α-β)*cos(α+β)}=cos^2α-cos(α-β)*cos(α+β)=cos^2α-cos^2α+sin^2β=sin^2β