Câu hỏi 5
Tính
$$\frac{\cos^4 75^\circ+\sin^4 75^\circ+3\sin^2 75^\circ\cos^2 75^\circ}{\cos^6 75^\circ+\sin^6 75^\circ+4\sin^2 75^\circ\cos^2 75^\circ}.$$
$$\frac{\cos^4 75^\circ+\sin^4 75^\circ+3\sin^2 75^\circ\cos^2 75^\circ}{\cos^6 75^\circ+\sin^6 75^\circ+4\sin^2 75^\circ\cos^2 75^\circ}.$$