SOLUTION: If 180° < &#952; < 270° and sin&#952; = p, express cos&#952; in terms of p.

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Question 975042: If 180° < θ < 270° and sinθ = p, express cosθ in terms of p.
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
If 180° < θ < 270° and sinθ = p, express cosθ in terms of p.
180° < θ < 270° means that θ is in Quadrant III, in which quadrant
tanθ is positive, cosθ and sinθ are both negative, so the answer will
be a negative number.

A well-known identity is

sinēθ + cosēθ = 1               <--We solve for cosθ:

        cosēθ = 1 - sinēθ 
                  _________ 
         cosθ = ą√1 - sinēθ

Since we know that the answer will be negative we
use only the negative sign, and substitute p for sinθ.
     
                  ______ 
         cosθ = -√1 - pē
         
Edwin