Mathematics
Senior High
2段目から3段目に行く計算方法を教えて欲しいです🙇♀️
余弦定理より
BC?%=D AB? + CA?-2AB·CAcosA
cos?20 = sin?0+cos?0 - 2sin 0 cos 0 ·
1
2
2倍角の公式などを使って整理すると
2sin?20 = sin20
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