Question

sin 80° /(sin 70°× cos30°-cos 70° × sin 30°) 2 ​

Answer 1

Ответ:

$\dfrac{sin80^\circ }{sin70^\circ \cdot cos30^\circ -cos70^\circ \cdot sin30^\circ }=\dfrac{sin80^\circ }{son(70^\circ +30^\circ )}=\dfrac{sin80^\circ }{sin100^\circ }=\\\\\\=\dfrac{sin(90^\circ -10^\circ )}{sin(90^\circ +10^\circ )}=\dfrac{cos10^\circ }{cos10^\circ }=1$