In ` A B C ,` if `(sinA)/(csinB)+(sinB)/c+(sinC)/b=c/(a b)+b/(a c)+a/(b c),` then the value of angle `A` is `120^0` (b) `90^0` (c) `60^0` (d) `30^0`

Explanation

`sinA/(csinB)+(sinB)/C+sinC/b=c/(ab)+b/(ac)+a/(bc)`

Sine law

`sinA/a=sinB/b=sinC/a=k`

`SinA=ak`

`SinB=bk`

`SinC=ck`

`(ak)/(cbk)+(bk)/(c)+(ck)/b=c/(ab)+b/(ac)+a/(bc)`

`k[b/c+c/b]=1/a[c/b+b/c]`

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