Question

tan90 is infinity and cotA=1/tanA. But, cot90=0, wheras cot90=1/tan90=1/infinity. This means that 1/ infinity=0. Cross multiplying, we get that: 1(or any other number)=0. How is this possible?

Answer 1

Answer :

WE get value of tan 90, As

we know tan 90 = $\frac{Sin90}{Cos90}$

And

Sin 90 = 1 And Cos 90 = 0 , So we get

tan 90 = $\frac{1}{0}$ = $\infty$ ( As we know any number divide by 0 gives infinity )

And

Cot 90 = $\frac{Cos90}{Sin90}=\frac{0}{1}=0$

So

We get

$\frac{1}{\infty }$ = 0

So after cross multiplication we get

First we write it As :

$\frac{1}{\infty }=\frac{0}{0}$ , So after cross multiplication we get

0 = 0