Q. 1

B is a right angle in ΔABC and is an altitude to hypotenuse. AB = 8, BC = 6. Find the area of ΔBDC.

Answer :

In ∆ABC, B is a right angle, AB = 8 and BC = 6

= 24 …(1)

In ∆ABC, B is a right angle and BD is an altitude,

In ∆ABC,

A + C = 90⁰ and,

In ∆BDC,

DBC + C = 90⁰

So, A = DBC …(2)

In ∆ABC and ∆BDC,

DAB DBC [from (2)]

ADB BDC [by right angles]

The correspondence ADB BDC is a similarity by AA corollary.

Areas of similar triangles are proportional to the squares of their corresponding sides.


Now, ADB + BDC = ABC

BDC = 8.64

The area of ∆BDC is 8.64.

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