Question

if (1+cotA).(1+cotB)=2
then A+B=?​

Answer 1

Answer:

Step-by-step explanation:

Cot (A+B) = (CotACotB-1)/(CotA + CotB )

We know......Cot(45)=1

so,          1=(CotACotB-1)/(CotA + CotB )

          CotACotB-1)=  (CotA + CotB )

          CotACotB-cotA-cotB=1

adding 1 to both sides.....we get

 

(cotA-1)(cotB-1)=2......proved

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