cot12 cot 38 cot 52 cot 60 cot 78=?
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(cos12/sin12)(cos38/sin38)(cos52/sin52)(cos60/sin60)(cos78/sin78)
{cos12*cos38*cos52*cos60*cos78}/{sin12*sin38*sin52*sin60*sin78}
{cos(90-78)*cos(90-52)*cos(90-38)*cos60*cos(90-12)}/{sin12*sin38*sin52*sin60*sin78}
{sin78*sin52*sin38*cos60*sin12}/{sin12sin38*sin52*sin60*sin78}
cot60=1/root3=1/(1.732)=.577
{cos12*cos38*cos52*cos60*cos78}/{sin12*sin38*sin52*sin60*sin78}
{cos(90-78)*cos(90-52)*cos(90-38)*cos60*cos(90-12)}/{sin12*sin38*sin52*sin60*sin78}
{sin78*sin52*sin38*cos60*sin12}/{sin12sin38*sin52*sin60*sin78}
cot60=1/root3=1/(1.732)=.577
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