" 3."cos510^(@)cos330^(@)+sin390^(@)cos120^(@)=-1

Prove that, cos510^(@)cos330^(@)+sin390^(@)cos120^(@)=-1 .

Prove that: cos510^(0)cos330^(@)+s in390^(@)cos120^(@)=-1

cos 510^@cos330^@+sin 390^@cos120^@ =

Show that cos510^@cos330^@-sin390^@cos120^@=-1/2

Prove that cos510^@cos330^@+sin390^@cos120^@=-1

sin150^(@).cos120^(@)+cos330^(@)*sin660^(@)=-1

Prove that: cos510^0cos 330^0+sin 390^0cos 120^0=-1.

Evaluate the following: i) cos120^(@)sin390^(@)+cos330^(@)cos150^(@) ii) sin^(2)(3pi)/(4)+cos^(2)pi/4+sec^(2)pi/3

Evaluate the following: i) cos120^(@)sin390^(@)+cos330^(@)cos150^(@) ii) sin^(2)(3pi)/(4)+cos^(2)pi/4+sec^(2)pi/3

sin120^(@)cos150^(@)-cos240^(@)sin330^(@)=