1. **Stating the problem:** We want to find the integral $$\int \frac{1}{1+\cos^4 t} \, dt$$ and analyze its behavior for graphing.
2. **Formula and approach:** There is no simple elementary antiderivative for $$\frac{1}{1+\cos^4 t}$$, so we consider rewriting or numerical methods for graphing.
3. **Rewrite the integrand:** Note that $$\cos^4 t = (\cos^2 t)^2$$ and use the identity $$\cos^2 t = \frac{1+\cos 2t}{2}$$.
4. Substitute:
$$\cos^4 t = \left(\frac{1+\cos 2t}{2}\right)^2 = \frac{1 + 2\cos 2t + \cos^2 2t}{4}$$
5. Use $$\cos^2 2t = \frac{1+\cos 4t}{2}$$:
$$\cos^4 t = \frac{1 + 2\cos 2t + \frac{1+\cos 4t}{2}}{4} = \frac{2 + 4\cos 2t + 1 + \cos 4t}{8} = \frac{3 + 4\cos 2t + \cos 4t}{8}$$
6. So the integrand becomes:
$$\frac{1}{1 + \cos^4 t} = \frac{1}{1 + \frac{3 + 4\cos 2t + \cos 4t}{8}} = \frac{1}{\frac{8 + 3 + 4\cos 2t + \cos 4t}{8}} = \frac{8}{11 + 4\cos 2t + \cos 4t}$$
7. The integral is now:
$$\int \frac{8}{11 + 4\cos 2t + \cos 4t} \, dt$$
8. This integral does not simplify easily to elementary functions, so for graphing, numerical integration or plotting the integrand $$y = \frac{1}{1+\cos^4 t}$$ is recommended.
9. **Graph features:** The function is periodic with period $$\pi$$ because $$\cos^4 t$$ has period $$\pi$$.
10. The function is always positive since denominator $$1 + \cos^4 t \geq 1$$.
11. The minimum value of the denominator is 1 (when $$\cos t = 0$$), so maximum of integrand is 1.
12. The maximum value of denominator is $$1 + 1 = 2$$ (when $$\cos t = \pm 1$$), so minimum of integrand is $$\frac{1}{2} = 0.5$$.
13. The graph oscillates between 0.5 and 1, positive, periodic.
14. For plotting, use $$y = \frac{1}{1+\cos^4 t}$$ with domain $$t \in [-2\pi, 2\pi]$$ to see multiple periods.
**Final answer:** The integral does not have a simple closed form in elementary functions, but the integrand simplifies to $$y = \frac{8}{11 + 4\cos 2t + \cos 4t}$$ which is positive and periodic with period $$\pi$$.
Integral Cos4 337F96
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