Prove that · `(cos 135^@ - cos 120^@)/(cos 135^@ +cos 120^@) = 3-2sqrt2`

Prove that: (cos 135^@ - cos120^@)/(cos 135^@ + cos120^@) =3-2 sqrt2 .

Prove that (i) " sin " 75^(@) =((sqrt(6)+sqrt(2)))/(4) (ii) (cos 135^(@) -cos 120^(@))/(cos 135^(@) +cos 120^(@)) =(3 -2sqrt(2)) (iii) " tan " 15^(@) +" cot " 15^(@) =4

Find the value of (sin 135^(@) - cos 120^(@))/(sin 135^(@) + cos 120^(@))

Prove that: sin 150^@ cos 120^@+ cos 330^@ sin 660^@= - 1 .

Prove that cos (A -120^@) + cos A + cos (A + 120^@) = 0 .

Prove that : cos^2 A+cos^2 (A+120^@)+ cos^2 (A-120^@)=3/2 .

Prove that cos(120^(@)+A)+cos(120^(@)-A)=-cosA

Prove that cos(120^(@)+A)+cos(120^(@)-A)=-cosA