A little late, sorry bout that. :/
11. G)
(Cosx)sqrt(sec²x – 1) = sinx
(Cosx)sqrt(1/cos²x – 1) = sinx (RI)
(Cosx)sqrt(1/cos²x – cos²x/cos²x) = sinx (cd)
(Cosx/1)(sinx/cosx) = sinx (PI)
sinx = sinx. QED
14. h)
Sec²x+csc²x = 1/(cos²x)(sin²x)
1/cos²x + 1/sin²x = 1/(cos²x)(sin²x) (RI)
sin²x/(cos²x)(sin²x) +cos²x/(cos²x)(sin²x) = 1/(cos²x)(sin²x) (cd)
1/(cos²x)(sin²x) = 1/(cos²x)(sin²x) QED
18. c)
(sinx)(secx)/(cscx)(sqrt(1-sin²x)) = tan²x
(sinx)(1) / (cosx/1)(1/sinx)(cos²x/1) = (sin²x)/(cos²x) (PI and RI and QI, wow!)
(sinx/1)(sinx/cosx) (kcc)
(sin²x)/(cos²x)=(sin²x)/(cos²x) QED
Hope this was easy enough to follow!
Tyson
