- 396 名前:132人目の素数さん [2024/03/15(金) 21:33:34.61 ID:ngMd7K2o.net]
- >>380
(sinA + sinB + sinC) (cosA + cosB + cosC−1) = sinA cosA + sinB cosB + sinC cosC = 2 sinA sinB sinC, sinA + sinB + sinC = 4 cos(A/2) cos(B/2) cos(C/2), cosA + cosB + cosC−1 = 4 sin(A/2) sin(B/2) sin(C/2), 辺々掛けて倍角公式。
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