SOLUTION: I do not understand why Sin(90 + X) = CosX I know how the 1st, 2nd ,3rd and 4th kwadrent work but i do not understand. Cos(90+X)=-SinX Tan(90+X0=-CotX Sin(180+X)=-SinX Cot(180

Algebra ->  Trigonometry-basics -> SOLUTION: I do not understand why Sin(90 + X) = CosX I know how the 1st, 2nd ,3rd and 4th kwadrent work but i do not understand. Cos(90+X)=-SinX Tan(90+X0=-CotX Sin(180+X)=-SinX Cot(180      Log On


   

Question 284287: I do not understand why Sin(90 + X) = CosX
I know how the 1st, 2nd ,3rd and 4th kwadrent work but i do not understand.
Cos(90+X)=-SinX
Tan(90+X0=-CotX
Sin(180+X)=-SinX
Cot(180+X)=CotX
Answer by vinaygar(1) About Me  (Show Source):
You can put this solution on YOUR website!
sin(90+x)=cosx
L.H.S=sin(90+x)=sin90+sinx
=1+sinx {since sin90=1}
=cosx{since 1+sinx=cosx}