Nilai dari Sin 80°-sin 40°/cos 80°- cos 40°
Matematika
herlinarahmayani
Pertanyaan
Nilai dari Sin 80°-sin 40°/cos 80°- cos 40°
1 Jawaban
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1. Jawaban Anonyme
Trigonometri.
sin A - sin B = 2 cos 1/2 (A + B) sin 1/2 (A - B)
cos A - cos B = -2 sin 1/2 (A + B) sin 1/2 (A - B)
(sin 80° - sin 40°) / (cos 80° - cos 40°)
= [2 cos 1/2 (80° + 40°) sin 1/2 (80° - 40°)] / [-2 sin 1/2 (80° + 40°) sin 1/2 (80° - 40°)]
= -(cos 60° sin 20°) / (sin 60° sin 20°)
= -cot 60°
= -1/3 √3