Evaluate ∫0πcos4(x)dx\int_0^{\pi} \cos^4(x) dx∫0πcos4(x)dx.
3π8\frac{3\pi}{8}83π
π4\frac{\pi}{4}4π
3π4\frac{3\pi}{4}43π
5π8\frac{5\pi}{8}85π