Question

in the fig ab =bc and ad1cd.prove that ac^2=2bc.cd​

Answer 1

Answer:

In △ADC,

AC

2

=AD

2

+DC

2

....(1)

In △ADB,

AB

2

=AD

2

+DB

2

∴AD

2

=AB

2

−DB

2

...(2)

In △ADC,

=(AB

2

−DB

2

)+(DB+BC)

2

....from (1) and (2)

=BC

2

−DB

2

+DB

2

+BC

2

+2DB.BC ...(As, AB=BC)

=2BC

2

+2DB.BC

=2BC(BC+DB)

=2BC.DC