SOLUTION: . If cosθ + sinθ = 2 cosθ ,then cosθ − sinθ = ? A. 2 sinθ B. cosθ 2 1 C. sinθ 2 1 D. None of the above

Algebra ->  Trigonometry-basics -> SOLUTION: . If cosθ + sinθ = 2 cosθ ,then cosθ − sinθ = ? A. 2 sinθ B. cosθ 2 1 C. sinθ 2 1 D. None of the above       Log On


   

Question 886190: . If cosθ + sinθ = 2 cosθ ,then cosθ − sinθ = ?

A. 2 sinθ
B. cosθ
2
1

C. sinθ
2
1

D. None of the above
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
cosθ + sinθ = 2cosθ
Add -cosθ to both sides of the equation

 cosθ + sinθ = 2cosθ
-cosθ          -cosθ
--------------------
        sinθ =  cosθ

Add -sinθ to both sides of the equation:

        sinθ =  cosθ
       -sinθ = -sinθ
       -------------
           0 =  cosθ - sinθ 

The answer is 0.  None of the above.

Edwin