(sin70°+sin20°)²-2tan70°cos²70°
={(sin70°+sin(90°-70°)}²-2(sin70°/cos70°)×cos²70°
=(sin70°+cos70°)²-2sin70°cos70°
=sin²70°+2sin70°cos70°+cos²70°-2sin70°cos70°
=sin²70°+cos²70°
=1
Mathematics
Senior High
(3)が分かりません。どーやって解くのか詳しく教えてください🙏
✓ 253 次の式の値を求めよ。
(1) sin40°+sin"50"
*(2)
*(3) (sin70°+sin 202tan70°cos"70°
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