Magnetic Activity and Period Variation Studies of the Short-period Eclipsing Binaries. III. V1175 Her, NSVS 2669503, and 1SWASP J133417.80+394314.4

New multi-band CCD light curves of three binaries W UMa-type V1175 Her, NSVS 2669503, and 1SWASP J133417.80+394314.4 are presented. Spectroscopic data for V1175 Her and NSVS 2669503 show that their spectral types are G7V and K4V, respectively. Photometric solutions of these three objects were obtained with the help of the Wilson-Devinney program. We find that V1175 Her is a semi-detached binary star with a hot spot located on the secondary component, while NSVS 2669503 and 1SWASP J133417.80+394314.4 are contact eclipsing binaries with contact factors off = 1.070 +/- 0.002% and f = 21.250 +/- 0.005%, respectively. Moreover, we found that the orbital period of V1175 Her is increasing at a rate of (+3.1 +/- 0.1) x 10(-7) daysyr(-1) . This increase may be attributed to a dM(1)/dt = -0.93 x 10(-7) M-circle dot yr-1 mass-transfer rate from the primary to the secondary component. Finally, we discuss the evolutionary stage of the component stars of these three systems.