SOLUTION: (1) Why is (cosx-sinx)^2 = to 1-2sinxcosx? That's the answer the prof. gave but I don't get that :/

Algebra ->  Trigonometry-basics -> SOLUTION: (1) Why is (cosx-sinx)^2 = to 1-2sinxcosx? That's the answer the prof. gave but I don't get that :/       Log On


   

Question 978214: (1) Why is (cosx-sinx)^2 = to 1-2sinxcosx?
That's the answer the prof. gave but I don't get that :/

Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
cos%5E2%28x%29-2%2Acos%28x%29sin%28x%29%2Bsin%5E2%28x%29
cos%5E2%28x%29%2Bsin%5E2%28x%29-2cos%28x%29sin%28x%29
Most basic of trigonometric identities,
1-2cos%28x%29sin%28x%29
DONE