Question 1171878
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Add increments of 2pi to the given angle to get a concurrent angle x = θ+k(2pi) for which x is between -pi/2 and +pi/2.  The reference angle is then abs(x).<br>
{{{-22pi/9+2pi = -4pi/9}}} is between -pi/2 and pi/2.<br>
The reference angle is {{{abs(-4pi/9) = 4pi/9}}}<br>
ANSWER: 4pi/9<br>