第12题.
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第12题.第12题.第12题.2sin20°+cos10°+tan20sin10°=2sin20°+cos10°+sin20sin10°/cos20°=2sin20°+(cos20°cos10°+si
第12题.
第12题.
第12题.
2sin20°+cos10°+tan20sin10°
=2sin20°+cos10°+sin20sin10°/cos20°
=2sin20°+(cos20°cos10°+sin20sin10°)/cos20°
=2sin20°+cos(20°-10°)/cos20°
=2sin20°+cos10°/cos20°
=(2sin20°cos20°+cos10°)/cos20°
=(sin40°+cos10°)/cos20°
=(sin40°+sin80°)/cos20°
=2sin[(40°+80°)/2]*cos[(40°-80°)/2]/cos20°
=2sin60°*cos20°/cos20°
=2*√3/2
=√3