Question 1079623
The tangent function is [ vertical ] / [  horizontal ]
The vertical displacement is zero in 2 cases:
{{{ theta = 0 }}}
{{{ theta = pi }}}
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{{{ tan(0) = 0/1 }}}
{{{ tan( pi ) = 0/(-1) }}}
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The horizontal displacement is zero in 2 cases,
{{{ theta = pi/2 }}}
{{{ theta = 3pi/2 }}}
This makes the tangent function undefined
{{{ tan( pi/2 ) }}} = infinity
{{{ tan( 3pi/2) }}} = infinity
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Hope this helps