How to prove $_2F_1\!\left( -\frac34, \frac34; \frac 14; \frac {\sqrt 3} 2 \right) = \sqrt {\frac {\sqrt 3 - 1} 2} - \frac {\Gamma^2(\frac 14)} {\sqrt \pi 2^{3/4} 3^{5/8}}$? (both approximately equal to -1.614289)
I tried using Mathematica and Hypergeometric identities and all attempts of them failed.