Q19 of 40 Page 8

In Fig., triangle ABC is right-angled at B. Given that AB = 9 cm, AC = 15 cm and D, E are the mid-points of the sides AB and AC respectively, calculate


(i) The length of BC


(ii) The area of ΔADE.

To Find: The length of BC and the area of ΔADE

Given:


ΔABC is right angled at B, AB = 9, AC = 15, and D, E are midpoints of sides AB and AC.


Concept Used:


Pythagoras Theorem: According to the Pythagoras theorem, Square of the hypotenuse of a right-angled triangle equal to the sum of squares of base and perpendicular.


Explanation:


AB = 9cm


AC = 15cm


D, E are midpoints of side AB and AC,


(i) by using Pythagoras theorem,




BC = √144


BC = 12cm


(ii) Area of ΔADE


Area


Area


Area


Area = 13.5 cm2


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