" (vi) "cos60^(@)=2cos^(2)30^(@)-1=1-2sin^(2)30^(@)

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

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^(@)

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

Evaluate : 3 cos^(2)60^(@)sec^(2)30^(@)-2 sin^(2)30^(@)tan^(2)60^(@)

Show that : cos 60^(@)=2cos^(2)30^(@)-1

Show that : cos 60^(@)=2cos^(2)30^(@)-1

Verify each of the following : (i) sin60^(@)cos30^(@)-cos60^(@)sin30^(@)=sin30^(@) (ii) cos60^(@)cos30^(@)+sin60^(@)sin30^(@)=cos30^(@) (iii) 2sin 30^(@)cos30^(@)=sin60^(@) (iv) 2sin45^(@)cos45^(@)=sin90^(@)

The value of sin^(2) 60^(@)+cos^(2)30^(@)-sin^(2)45^(@) is _________

cos120^(@)=cos(90^(@)+30^(@)) =-sin30^(@)=-(1)/(2)

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