Question

Pls answer the attachment for heavens sake...question number 11 option 2

Answer 1

Cos (180°-55°)=-cos 125°
cos(180°+24°)=-cos 24°
cos (360°-60°)=cos 60°
cos 24°-cos 125°+cos 125°-cos 24°+cos 60°
cos 60°=1/2