Math, asked by guptavijay0773, 1 year ago

In a figure AD is the median of a triangle abc and AL transversal to BC then prove that area of ABD equal to area of ACD equal to half of area of ABC

Answers

Answered by tukumaharanagirish
3

Answer:


Step-by-step explanation:

Given,

AD is the median

So,

BD=DC,

<BAD=<DAC

To prove :ar(ABD)=ar(CAD)

Proof,

In ABD and CAD,

BD=DC(given)

<BAD=<CAD(given)

AD=AD(given)

Thus,ABD=~CAD

So,ar(ABD)=ar(CAD)

=1/2ar(ABC)

Answered by Anonymous
1

(a) Given:

∆ABC in which AD is the median. P is any point on AD. Join PB and PC.

To prove:

(i) Area of ∆PBD = area of ∆PDC.

(ii) Area of ∆ABP = area of ∆ACP.

Proof:

From fig (1)

AD is a median of ∆ABC

So, ar (∆ABD) = ar (∆ADC) …. (1)

Also, PD is the median of ∆BPD

Similarly, ar (∆PBD) = ar (∆PDC) …. (2)

Now, let us subtract (2) from (1), we get

ar (∆ABD) – ar (∆PBD) = ar (∆ADC) – ar (∆PDC)

Or ar (∆ABP) = ar (∆ACP)

Hence proved.

(b) Given:

∆ABC in which DE || BC

To prove:

(i) area of ∆ACD = area of ∆ ABE.

(ii) Area of ∆OBD = area of ∆OCE.

Proof:

From fig (2)

∆DEC and ∆BDE are on the same base DE and between the same || line DE and BE.

ar (∆DEC) = ar (∆BDE)

Now add ar (ADE) on both sides, we get

ar (∆DEC) + ar (∆ADE) = ar (∆BDE) + ar (∆ADE)

ar (∆ACD) = ar (∆ABE)

Hence proved.

Similarly, ar (∆DEC) = ar (∆BDE)

Subtract ar (∆DOE) from both sides, we get

ar (∆DEC) – ar (∆DOE) = ar (∆BDE) – ar (∆DOE)

ar (∆OBD) = ar (∆OCE)

Hence proved.

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