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How does my book go from this step to the next (trig)

  • Thread starter frasifrasi
  • Start date
276
0
OK, in an example, we are given:

"T(θ)= 2 cos^2 (θ) +sin^2 (θ) − sin (θ) + 3
=cos^2 (θ) − sin θ + 4.
Then Tθ(θ)= −2 cos θ sin θ − cos θ =
−cos θ(2 sinθ + 1)"

can anyone explain what happened from step 1 to 2--i am completely lost?

Thanks.
 

Answers and Replies

NateTG
Science Advisor
Homework Helper
2,448
5
OK, in an example, we are given:

"T(θ)= 2 cos^2 (θ) +sin^2 (θ) − sin (θ) + 3
=cos^2 (θ) − sin θ + 4.
Then Tθ(θ)= −2 cos θ sin θ − cos θ =
−cos θ(2 sinθ + 1)"

can anyone explain what happened from step 1 to 2--i am completely lost?
[tex]\sin^2 \theta + \cos^2 \theta = 1 [/tex]
so
[tex]\sin^2 \theta = 1 - \cos^2 \theta[/tex]
Now, substitute in for step 1 and simplify.
 
276
0
Geez, I am embarassed.
 

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