Question 1114122
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cos(A) = {{{-1/sqrt(2)}}}   ====>


cos(A) = {{{-sqrt(2)/2}}}  ====>


A = {{{3pi/4}}}   or   A = {{{5pi/4}}}.


<U>Answer</U>.  There are two solutions in the interval [0,{{{2pi}}}):  A = {{{3pi/4}}}   or   A = {{{5pi/4}}}.
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