Câu `15` (thiếu đề)

Câu `16`

`P=((sin alpha+tan alpha)/(cos alpha+1))^2+1`

`P=((sin alpha+(sin alpha)/(cos alpha))/(cos alpha+1))^2+1`

`P=[(sin alpha(1+1/(cos alpha)))/(cos alpha+1)]^2+1`

`P=((sin alpha . (cos alpha+1)/(cos alpha))/(cos alpha+1))^2+1`

`P=((sin alpha)/(cos alpha))^2+1`

`P=tan^2 alpha+1`

`P=1/(cos^2 alpha)`

`->bbC`

Câu `17`

`P=tan alpha((1+cos^2 alpha)/(sin alpha)-sin alpha)`

`P=tan alpha (1+cos^2 alpha-sin^2 alpha)/(sin alpha)`

`P=tan alpha . (cos^2 alpha+cos^2 alpha)/(sin alpha)`

`P=(sin alpha)/(cos alpha) . (2cos^2 alpha)/(sin alpha)`

`P=2cos alpha`

`->bbB`