SOLUTION: the expression cos2 40+sin2 40 is equivalent to 1. (1) 2. (2) 3. Cos0 4. Cos80

Algebra ->  Trigonometry-basics -> SOLUTION: the expression cos2 40+sin2 40 is equivalent to 1. (1) 2. (2) 3. Cos0 4. Cos80      Log On


   

Question 739575: the expression cos2 40+sin2 40 is equivalent to
1. (1)
2. (2)
3. Cos0
4. Cos80
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Always always ALWAYS remember that

is true for all values of x

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Note: this identity is among the first you learn in a trig class because it's based on the pythagorean theorem (that you learn in a previous algebra class). From there, you build a lot more trig identities.
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This will lead you to choice A as the answer since



turns into



after you plug in x = 40