$$\lim_{x \to \infty} \cos^{4}{\left(x \right)} = \left\langle 0, 1\right\rangle$$ $$\lim_{x \to 0^-} \cos^{4}{\left(x \right)} = 1$$ More at x→0 from the left $$\lim_{x \to 0^+} \cos^{4}{\left(x \right)} = 1$$ More at x→0 from the right $$\lim_{x \to 1^-} \cos^{4}{\left(x \right)} = \cos^{4}{\left(1 \right)}$$ More at x→1 from the left $$\lim_{x \to 1^+} \cos^{4}{\left(x \right)} = \cos^{4}{\left(1 \right)}$$ More at x→1 from the right $$\lim_{x \to -\infty} \cos^{4}{\left(x \right)} = \left\langle 0, 1\right\rangle$$ More at x→-oo