Question

if tan alpha* tan bita =1, then value of cos (alpha+bita)is

Answer 1

Step-by-step explanation:

If

$\tan( \alpha) \tan( \beta ) = 1$

then,

$\tan( \alpha ) = 1 \div \tan( \beta ) = \cot( \beta ) .$

This means that

$\beta + \alpha = {90}^{o}.$

Which implies that

$\cos( \alpha + \beta ) = \cos( {90}^{o} ) = 0$