In triangle ABC, side AB is 13 cm, height BD divides the base of AC into segments AD 5 cm. CD 16 c. Find a BC side?

The height BD divides an arbitrary triangle ABC into two right-angled triangles ABD and CBD. From the Pythagorean theorem we find the height BD.

AB² = BD² + AD²

BD² = 13² – 5²

BD² = 169 – 25

BD² = 144

BD = 12 cm.

Consider the CBD triangle. Also, by the Pythagorean theorem, we find the hypotenuse of BC.

BC² = CD² + BD²

BC² = 16² + 12²

BC² = 256 +144

BC² = 400

BC = 20.

Answer: BC side = 20 cm.



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