(3)quad cos60=cos^(2)30-sin^(2)30

Verify that: ( i ) cos60o=cos^(2)30o-sin^(2)30o=(1)/(2) (ii) 4(sin^(4)30o+cos^(4)30o)-3(cos^(2)45o-sin^(2)90o)=2

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

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

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

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^(@)

Prove that : cos^(2)30^(@)-sin^(2)30^(@)=cos60^(@)

Prove that : cos^(2)30^(@)-sin^(2)30^(@)=cos60^(@)

If it right to say cos(60^(@)+30^(@))=cos60^(@)cos30^(@)-sin60^(@)sin30^(@)

Find the value of cos60^(@) cos 30^(@)-sin 60^(@) sin 30^(@)