B612 cjcosplaycoscos.

tansincos 1. 2.090 .

cos xx.

Understanding the Context

sincos sinAA .

coscos=x/rRt ABCC=90A ...

cos2x/3sinsin

sincossinxcosx:sin (/2+)=cos cos (/2+)=sin .

Key Insights

cos coscos.

sincossincos1. sin (x) = cos (/2 - x)cos (x) = sin (/2 - x)

20COSPLAYcoserAPP ~ COSCOS.