В равнобедренном треугольнике ABC с основанием AC проведена высота BM и угол ABM равен 30 градусов боковая сторона AB равна 15 см найдите длину отрезка ЭТО

Spasskaya Tower was built in 1491 during the reign of Ivan III architect Pietro Antonio Solari, as evidenced by the white stone slabs with commemorative inscriptions that are installed above the entrance gate of the tower. The outside of the tower inscription is in Latin; the inside - in Russian: "In the summer 6999 [1491] July by God's grace made there was this loophole command Ivan the Tsar and autocrat of all Russia and Grand Duke Volodimirskaya and Moscow and Novgorod and Pskov and Tver and Ugra and Vyatka and Perm and Bulgarian and other in 30 States, his summer, as did Peter Anthony Solari from the city of Mediolanum" (Milan). Before the construction of the existing tower on this spot stood the Frolovskaya Barbican white-stone Kremlin 1367. When repairing the Barbican in 1464-1466, D. V. Yermolin mounted on her white stone reliefs depicting the patrons of the Moscow princes - saints George and Demetrios; these reliefs was moved to the new tower, where they remained until the seventeenth century

The Moscow Kremlin
The first settlements in the territory of the Moscow Kremlin belong to the Bronze Age (II millennium BC. E.). The modern Archangel Cathedral was found Finno-Ugric settlement from the early Iron Age (the second half of the I millennium BC. E.). At this time, the settlement Dyakova type occupies the center of the upper floodplain terraces Borovitsky Hill (near modern Cathedral Square), and may have taken to strengthen. From the north-east village was protected by two ravines - one to the north of the current Trinity gates went down to the river Neglinnoy, another lay between Peter's and the Second Nameless Tower modern Kremlin.In 1991, the Kremlin became the residence of the President of Russia. In the 1990s, the Kremlin carried out major restoration work, which resulted in the restored Red Porch Faceted Chamber, Alexander restored and St. Andrew's Hall of the Grand Kremlin Palace, carried out the restoration of the building of the Senate. [46] In 1996-2000 was carried out restoration of the Kremlin walls and towers [47]. In July 2014, President Vladimir Putin proposed to demolish the administrative 14th Corps Ivan square of the Moscow Kremlin and restore the stand in his place and Miracles Ascension Monastery.