Вычислите: √2 (sin70°+sin20°)/sin80°cos15°-cos80°cos75°

Question

Вычислите: √2 (sin70°+sin20°)/sin80°cos15°-cos80°cos75°

Answer 1

√2*1/2sin45cos25/(sin80cos15-cos80sin15)=
=√2*1/2*1/√2cos25/sin(80-15)=1/2cos25/sin65=1/2cos25/cos25=1/2