Triangle ABC is isosceles with base AC. Find the base if the median BM is 12 cm and the side is 13 cm.

Since the triangle ABC is isosceles, the median of the BM is also the height, then the BM is perpendicular to the AC.

From the right-angled triangle BMC, according to the Pythagorean theorem, we determine the leg CM.

CM ^ 2 = BC ^ 2 – BM ^ 2 = 13 ^ 2 – 12 ^ 2 = 169 – 144 = 25.

CM = 5 cm.

Then the base AC = 2 * CM = 2 * 5 = 10 cm.

Answer: The length of the base of the AC = 10 cm.



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