Q14 of 16 Page 133

Triangle ABC is right angled at B. AD and CE are the two medians drawn from A and C respectively. If AC = 5cm, AD = cm. Find the length of CE.

We have


Given that,


∆ABC is a right-angled triangle at B.


BD = DC


AE = EB


Values:


AC = 5 cm



To find Length of CE.


Take ∆ABC,


Apply Pythagoras theorem in ∆ABC, we get


AC2 = AB2 + BC2


(5)2 = (2BE)2 + BC2


25 = 4(BE)2 + BC2 …(i)


Take ∆ABD,


Apply Pythagoras theorem in ∆ABD, we get


AB2 + BD2 = AD2 …(ii)





Put the values in the above equation, we get



45 = 16BE2 + BC2 …(iii)


For solving equations (i) and (iii), multiply equation (i) with 4.


(i) 100 = 16BE2 + 4BC2 …(iv)


Solve equations (iii) and (iv),





Take 25 = 4(BE)2 + BC2,


AC2 = 4BE2 + BC2


4BE2 = AC2 - BC2







Now, in ∆BEC, applying Pythagoras theorem, we can write


BE2 + BC2 = CE2





CE2 = 20


CE = √20


CE = √(2 × 2 × 5)


CE = 2√5


Thus, length of CE = 2√5 cm.


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