Tg75°-tg15° ctg11°+ctg34°

Question

Tg75°-tg15°
ctg11°+ctg34°

Answer 1

Ctg11+ctg34=sin(34+11)/sin11*sin34=sin45/sin11*sin34=√2/(cos(34-11)-cos45)=
=√2/(cos23-√2/2)
tg75-tg15=tg(90-15)-tg15=ctg15-tg15=cos30/sin15cos15=2cos30/sin30=2ctg30=2√3