Question

1 - sin37⁰ * sin143⁰ - cos²37⁰=

пожалуйста помогите​

Answer 1

Формулы:

$\sin(180^\circ-\alpha )=\sin\alpha \\\sin^2\alpha +\cos^2\alpha =1$

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$1-\sin37^\circ\cdot \sin143^\circ-\cos^237^\circ=\\\\=1-\sin37^\circ\cdot \sin(180^\circ-37^\circ)-\cos^237^\circ=\\\\=1-\sin37^\circ\cdot \sin37^\circ-\cos^237^\circ=\\\\=1-\Big(\sin^237^\circ+\cos^237^\circ\Big)=1-1=0$

Ответ: 0.