In triangle ABC it is known that AB = BC, the bisector BL is 5. The area of triangle ABC is 50√2. Find the side length BC.

The bisector BL splits triangle ABC into two equal right-angled triangles ABL and LBC.

Therefore, the sides of these triangles are pairwise equal.

Because area of triangle ABC:

S = (1/2) * AC * BL = (1/2) * AC * 5 = 5 * AC / 2 = 50 * √2, then AC = 20 * √2.

AL = LC = (1/2) * AC = 10 * √2.

By the Pythagorean theorem, AB² = BL² + AL² = 5² + (10 * √2) ² = 225,

AB = 15.

By the condition AB = BC = 15.

Answer: BC = 15 units.



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