2sin20°+(cos10°/cos20°)

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2sin20°+(cos10°/cos20°)
2sin20°+(cos10°/cos20°)

2sin20°+(cos10°/cos20°)
2sin20°+(cos10°/cos20°)=[2sin20°cos20°+cos10°]/cos20°
=[sin40°+sin80°]/cos20°=[2sin60°*cos20°]/cos20°=√3

2sin20°+(cos10°/cos20°)
=
(2sin20°cos20°+cos10°)/cos20°
=(sin40°+cos10°)/20°
=(sin40°+sin80°)/20°
=【2sin(40°+80°)/2*cos(40°-80°)/2】/cos20°
=2sin60°cos20°/cos20°
=√3