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# Soooo confused about calculus?!?!?

f ''(θ) = sin θ + cos θ, f(0) = 4, f '(0) = 1

Find:

f(θ) =

I really dont even know where to start or where to find f(θ)!!

### 1 Answer

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- StephenLv 68 years agoFavorite Answer
Integrate once to get f'(θ)

Integrate twice to get f(θ)

Recall that the integral of sin x = - cos x and the integral of cos x = sin x

In this case f'(θ) = -cos θ + sin θ + C

f(θ) = -sin θ - cos θ + C*θ + D

f(0) = 4, = 0 -1 + 0 + D = 4

so D = 5

if f'(0) = 1 then

1 = -1 + 0 + C

so C = 2

Summary:

f(θ) = -sin θ - cos θ + 2θ + 5

Hope this is useful. Good luck.

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