Question

if a + b is equal to 45 degrees then (1-cotA) (1-cotB) is​

Answer 1

Your answer

A + B = 45

So,

cot 45 = cot (A + B) = (cot A * cot B – 1)/(cot A + cot B)

or, cot A + cot B = cot A * cot B – 1

or, cot A * cot B – (cot A + cot B) = 1

Now, (cot A – 1)(cot B – 1) = cot A * cot B – (cot A + cot B) + 1 = 1 +1 = 2