cos10+根号3sin10
=2(sin30cos10+cos30sin10)
=2sin40
tan70*2sin40
=2sin70sin40/cos70
=2cos20sin40/sin20
=2cos20*2sin20cos20/sin20
=4cos20^2
=4*(cos40+1)/2
=2cos40+2
tan70°(cos10°+根号3sin10°)-2cos40°
=2cos40+2-2cos40
=2