✨ 最佳解答 ✨
公式錯誤
sin2@=2sin@cos@
cos2@=2cos²@-1
=1-2sin²@=cos²@-sin²@
sin5°+sin10°. sin5°+2sin5°cos5°
------------------- = -----------------------------
1+cos5°+cos10°. cos²5°+sin²5°+cos5°
+cos²5°-sin²5°
sin5°+2sin5°cos5. sin5°(1+cos5°)
= --------------------------- = --------------------------
2cos²5°+cos5°. cos5°(1+cos5°)
=tan5°
非常謝謝你!!