सत्यापित करो कि ` cos 60^(@) =(1- tan^(2) 30^(@))/(1+ tan^(2) 30^(@))=(1)/(2)`

Explanation

दिया है ,
` RHS=(1- tan^(2) 30^(@))/(1+ tan^(2) 30^(@)) =(1-(1//sqrt(3))^(2))/(1+(1//sqrt(3))^(2))=(1-(1)/(3))/(1+(1)/(3))=(2//3)/(4//3)=(1)/(2)`
`LHS=cos 60^(@)=(1)/(2)`
`:. ` LHS=RHS
अतः ` cos 60^(@)=(1- tan^(2) 30^(@))/(1+ tan^(2) 30^(@))=(1)/(2)`