If A+B=225°, then find the value of (cot A/(1+cot A))(cot B/(1+cot B))?

1 Answer
Jun 3, 2018

ans=1/2

Explanation:

rarrA+B=225°

rarrcot(A+B)=cot225°=cot(180°+45°)=cot45°=1

rarr(cotA*cotB-1)/(cotA+cotB)=1

rarrcotA*cotB-1=cotA+cotB

rarrcotA+cotB+1=cotA*cotB....(1)

Now,

rarr(cotA*cotB)/((1+cotA)*(1+cotB))

=(cotA*cotB)/(1+cotB+cotA+cotA*cotB)

=(cotA*cotB)/(cotA*cotB+cotA*cotB)....using (1)

=(cancel(cotAcotB))/(2cancel(cotAcotB))=1/2