
展开全部
2sin20+cos10+sin20sin10/cos20
=(sin40+cos10)/cos20
=(sin40+sin80)/cos20
=2sin60cos20/cos20
=√3
=(sin40+cos10)/cos20
=(sin40+sin80)/cos20
=2sin60cos20/cos20
=√3
展开全部
原式=2sin20+cos10+tan20*sin10
=2sin20+cos10+(sin20/cos20)*sin10
=(2sin20*cos20+cos10*cos20+sin20*sin10)/cos20
=(sin40+cos(20-10))/cos20
=(sin40+cos10)/cos20
=(sin40+sin80)/cos20
=2sin60*cos20/cos20
=2sin60
=根号3
=2sin20+cos10+(sin20/cos20)*sin10
=(2sin20*cos20+cos10*cos20+sin20*sin10)/cos20
=(sin40+cos(20-10))/cos20
=(sin40+cos10)/cos20
=(sin40+sin80)/cos20
=2sin60*cos20/cos20
=2sin60
=根号3
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展开全部
2sin160-cos170-tan160sin170
=2sin20+cos10+tan20sin10
=(2sin20cos20+cs20cos10+sin20sin10)/cos20
=(sin40+cos10)/cos20
=(cos50+cos10)/cos20
=2cos30cos20/cos20
=2cos30
=√3.
=2sin20+cos10+tan20sin10
=(2sin20cos20+cs20cos10+sin20sin10)/cos20
=(sin40+cos10)/cos20
=(cos50+cos10)/cos20
=2cos30cos20/cos20
=2cos30
=√3.
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