Problem:
Trigonometric expressions
1) 2 tan (theta /2)=
2) 2 tan theta Sin ^2 (theta /2)=
3) 2 Cos (45 + x) Cos (45-x)=
4) (Sin 3 x - 3 Sin x )/ ( Cos 3 x + 3 Cos x) =
5) 2 tan (theta /2) / { 1 + tan ^2 (theta /2) } =
6) Find the least positive value of theta such that
tan (45+ theta ) - 3 tan theta =2