In Δ ABC, seg AD is a median (D is the midpoint of side BC). If \(AB^2 + AC^2 = 122\) and BC = 10, find AD.
Q.2 (B)(2) In Δ ABC, seg AD is a median (D is the midpoint of side BC). If \(AB^2 + AC^2 = 122\) and BC = 10, find AD.
Q.2 (B)(2) In Δ ABC, seg AD is a median (D is the midpoint of side BC). If \(AB^2 + AC^2 = 122\) and BC = 10, find AD.
Best answer
Answer: AD = 6
D is the midpoint of BC, so BD = \(\dfrac{10}{2}\) = 5.
By Apollonius theorem, \(AB^2 + AC^2 = 2AD^2 + 2BD^2\).
\(122 = 2AD^2 + 2(5)^2 = 2AD^2 + 50 \Rightarrow 2AD^2 = 72 \Rightarrow AD^2 = 36 \Rightarrow AD = 6\).
Log in or create a free account to answer this question.