Question Number 100491 by bobhans last updated on 27/Jun/20

Answered by bramlex last updated on 27/Jun/20

let arccot (1/2) = z ⇒ cot z = (1/2) let arccot (2/3) = w ⇒cot w = (2/3) ⇔tan (z+w) = ((tan z+tan w)/(1−tan z.tan w)) = ((2+(3/2))/(1−2.(3/2))) = (7/(2−6)) = −(7/(4 )) ■