Ayuda?

2. )

[tan(x) + cos(x)] / sen(x) =

[sen(x) / cos(x)] / sen(x) + cos(x) / sen(x) =

[sen(x) / cos(x)]×[1 / sen(x)] + ctg(x) =

1 / cos(x) + ctg(x) =

sec(x) + ctg(x)

3.

)

sen(x + y) + sen(x - y) =

sen(x)cos(y) + cos(x)sen(y) + sen(x)cos(y) - cos(x)sen(y) =

2sen(x)cos(y)

4.

)

csc(x) / [tan(x) + ctg(x)] =

[1 / sen(x)] / [(sen(x) / cos(x)) + (cos(x) / sen(x)] =

[1 / sen(x)] / [(sen²(x) + cos²(x)) / sen(x)cos(x) =

[1 / sen(x)] × [sen(x)cos(x)] / 1 =

cos(x)

Salu2.

Suerte.

: ).