sin 10 sin 30 sin 50 sin 70

Prove that \sin 10 \sin 20 \sin 30=\sin 10 \sin 10 \sin 100? https://math.stackexchange.com/questions/442209/prove-that-sin-10-sin-20-sin-30-sin-10-sin-10-sin-100 Write \displaystyle\sin10\sin100=\sin10\sin(90+10)=\sin10\cos10=\frac{1}{2}\sin20=\sin20\sin30. di suatu kelas 8 terdapat 30 siswa