Question

If A+B =45 then prove that
i) CotA.CotB-CotA-CotB=1​

Answer 1

Explanation:

`if A+B=45\\tan(A+B)=tan(45)\\(tanA+tanB)/(1-tanA.tanB)=1\\ \implies tanA+tanB=1-tanA.tanB\\(1)/(cotA)+(1)/(cotB)=1-(1)/(cotA)(1)/(cotB), \{tanX=(1)/(cotX) \}\\ cotA+cotB=cotA.cotB-1\\cotA.cotB-cotA-cotB=1.`