Question

show that rr1 cotA/2=Delta​

Answer 1

Answer:

To prove: rr

1

cot

2

A

=S

We know,

tan

2

A

=

s(s−a)

(s−b)(s−c)

⟹cot

2

A

=

(s−b)(s−c)

s(s−a)

Also, r=

s

S

,r

1

=

s−a

S

where S=

s(s−a)(s−b)(s−c)

Now,

rr

1

cot

2

A

=

s(s−a)

S

2

(s−b)(s−c)

s(s−a)

=

s(s−a)

s(s−a)(s−b)(s−c)

(s−b)(s−c)

s(s−a)

=

(s−b)(s−c)

(s−b)

2

(s−c)

2

s(s−a)

=

s(s−a)(s−b)(s−c)

=S

Mark me as brainliest

Answer 2

Answer:

I hope my answer is correct