Câu hỏi 84
Chứng minh rằng
$$\cos(56^\circ)\cdot\cos(2\cdot56^\circ)\cdot\dots\cdot\cos(2^{23}\cdot56^\circ)=\frac1{2^{23}}.$$
$$\cos(56^\circ)\cdot\cos(2\cdot56^\circ)\cdot\dots\cdot\cos(2^{23}\cdot56^\circ)=\frac1{2^{23}}.$$
MathNet 2014 Câu hỏi 84
Math Olympiad Vault · MathNet 2014