Monday, 21 November 2016

Prove trigonometry identity for secxquadsinx



I'm trying to prove this equality but I' stuck at the second step.



Please give me some hints or other ways to proceed.




tan2x+cos2xsinx+secxsecxsinxsinx=xcosx=yx2y2+y4y2xyy+1y1yx=1xyy(1)(x2+y4y2)(xy+1y)(2)x2+y4y(xy+1)(3)


Answer



The key is to see that (x+y)(xy)=x2y2.
tan2x+cos2xsinx+secx=tan2x+11+cos2xsinx+secx=sec2xsin2xsinx+secx=secxsinx.


No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find limh0sin(ha)h without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...