cotAcosA=cscA-sinA
I prefer moving the left side of the equation, doing nothing to the right side
[tex]\frac{cosA}{sinA}(cosA)=cscA-sinA[/tex]
Now multiply cosA by itself:
[tex]\frac{cos^2A}{sinA}=cscA-sinA[/tex]
doing the conversion
cos²x+sin²x=1
[tex]\frac{1-sin^2A}{sinA}=cscA-sinA[/tex]
separate the two
[tex]\frac{1}{sinA}-\frac{sin^2A}{sinA}=cscA-sinA[/tex]
since:
[tex]\frac{1}{sinA}=cscA[/tex]
and
[tex]\frac{sin^2A}{sinA}=sinA[/tex]
substitute:
cscA-sinA=cscA-sinA
Hope this helps =)
