In the given Fig, ABC is a right triangle, right angled at B. AD and CE are two medians drawn from A and C respectively. If AC = 5 cm and find the length of CE.
Let BQ = QP = PC = x
Then, BP = 2x and BC = 3x
In ∆ABQ,
AQ2 = AB2 + BQ2
[Using Pythagoras theorem]
⇒ AQ2 = AB2 + x2 ...(i)
In ∆ABP,
AP2 = AB2 + BP2
[Using Pythagoras theorem]
⇒ AP2 = AB2 + (2x)2
⇒ AP2 = AB2 + 4x2 ...(ii)
In ∆ABC,
AC2 = AB2 + BC2
[Using Pythagoras theorem]
⇒ AC2 = AB2 + (3x)2
⇒ AC2 = AB2 + 9x2 ...(iii)
Multiplying (ii) by 8
8AP2 = 8AB2 + 32x2 ...(iv)
Multiply (iii) by 3
3AC2 = 3AB2 + 21x2 ...(v)
Multiply (i) by ‘5’.
5AQ2 = 5AB2 + 5x2 ...(vi)
Adding, (v) and (vi), we get
3AC2 + 5AQ2 = (3AB2 + 5AB2)+ (27x2 + 5x2)
⇒ 3AC2 + 5AQ2 = 8AB2 + 32x2 [from (iv)]
3AC2 + 5AQ2 = 8AP2.