`cos^(2)30^@-sin^(2)30^@=cos60^@`

Prove that cos 60^(@)=cos^(2)30^(@)-sin^(2)30^(@) .

sin^(2)30+cos^(2)60

Show that (i) cos60^(@)*cos30^(@)-sin60^(@)*sin30^(@)=cos90^(@) (ii) cos60^(@)=1-2sin^(2)30^(@)=2cos^(2)30^(@)-1 (iii) (tan60^(@)-tan30^(@))/(1+tan60^(@)*tan30^(@))=tan30^(@)

Show that : cos^(2)60^(@)-sin^(2)60^(@)=-sin30^(@)

Show that : cos^(2)60^(@)-sin^(2)60^(@)=-sin30^(@)

Evaluate The following : sin 60^@ cos 30^@ + sin 30^@ cos 60^@

Verify that: (i) cos60^@=cos^2 30^@-sin^2 30^@=1/2

Evaluate : (5 cos^(2)60^@+4cos^(2)30^@ - tan^(2)45^@)/(sin^(2) 30^@+cos^2 60^@)

"(1) "sin60^(@)cos30^(@)+sin30^(@)cos60^(@)

Evaluate : |(sin30^@, cos30^@),(-sin60^@, cos60^@)| .