Question 860585
{{{ ( 7*pi )/2 }}}
You know that {{{ ( 4*pi )/2 = 2*pi }}}
is a full circle and brings you back
to the zero angle
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Knowing also that
{{{ ( 7*pi )/2 = ( 3*pi )/2 + ( 4*pi )/2 }}}
This becomes
{{{ ( 7*pi )/2 = ( 3*pi )/2 + 2*pi }}}
{{{ ( 7*pi ) / 2 = ( 3*pi )/2 }}}
So, {{{ ( 3*pi )/2 }}} is the smallest positive 
angle that is co-terminal with
{{{ ( 7*pi ) /2 }}}
{{{ ( 7*pi ) / 2 = ( 3*pi ) / 2 }}}
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{{{ -7*pi )/3 }}}
You had to go in a negative ( CW ) direction
to get this angle. You know that:
{{{ - ( 6*pi ) / 3 = - 2*pi }}}
Is a fill circle. You just went in a negative
direction to get there.
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Likewise,
{{{ - ( 7*pi ) / 3 = - pi / 3 - ( 6*pi ) / 3 }}}
This becomes
{{{ - ( 7*pi ) / 3 = - pi / 3 - 2*pi }}}
{{{ - ( 7*pi ) / 3 = - pi / 3 }}}
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Now you just have to convert this to a positive
angle. If you went {{{  2*pi }}} and then backed up
{{{ - pi / 3 }}} that would be the same angle, so
I can say:
{{{ - pi / 3 =  ( 6*pi ) / 3 - pi / 3 }}}
{{{ - pi / 3 = ( 5*pi ) / 3 }}}
So, no I can say:
{{{ - ( 7*pi ) / 3 = ( 5*pi ) / 3 }}}