If tan^-1x + tan^-1y + tan^-1z= pi or pi/2
then prove x+y+z=xyz or
xy +yz+zx=1

Arctan x + arctan  y = arctan (x+y / 1-xy)

arctan (x+y / 1-xy) + arctan z = arctan (x + y + z - xyz/ 1 - xy - zx - zy)

If tan pi = 0 , then the de numerator is also 0 , solve it and you will get it

tan pie/2 = infinity, denominator = 0 , solve it and you will get it

hope this helps

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.

Dang i wish i could , good luck (i’m bad at math)