Fourier Transform of Cosine

Question

I want to calculate the Fourier Transform of a cosine signal that is$\;\mathfrak{F}\{ cos(\frac{7\pi}{2}t)\}\:?$

In some sources it is given as (1) $\;\mathfrak{F}\{ cos(w_0t)\}\:=\:\pi [\delta(w-w_0)+\delta(w+w_0)]$

Other sources have (2) $\;\mathfrak{F}_t[ cos(2\pi k_0t)](k)\:=\:\frac{1}{2} [\delta(k-k_0)+\delta(k+k_0)]$

(1) is from the Signals&Systems book by Oppenheim, (2) is from Wolfram FourierTransformCosine. How can these two representations be equivalent? I will appreciate any help.