Question

If AD = 12 units, BD = 15 units, and AC = 4 units, what is the length of BC?

Answer 1

Answer:

The answer to your question is:  BC = √65 or 8.05 u

Step-by-step explanation:

Data

AD = 12 u

BD = 15 u

AC = 4 u

BC = ?

First calculate the length of AB using the pythagorean theorem

 BD² = AB² + AD²

 AB² = BD² - AD²

 AB² = 15² - 12²

 AB² = 225 - 144

 AB² = 81

 AB = 9 u

Now, use the pythagorean theorem to find BC

 AB² = BC² + AC²

 BC² = AB² - AC²

 BC² = 9² - 4²

 BC²  = 81 - 16

 BC² = 65

 BC = √65 or 8.05 u