Вычислите: sin 13п/4; cos(405˚); tg (-11п/6); ctg 5п/4

Sin 13π/4 = sin(2π+  5π/4) = sin 5π/4 = -1/√2

cos405°=cos (360+45)=cos45°=π/4=√2/2

tg(-11π/6)=-tg(11π/6)=-tg(2π-π/6)=-tg(-π/6)=tgπ/6=√3/3

ctg 5π/4 = ctg (π+π/4 )= ctg π/4 = 1