B= 2019 cos bình 35° + sin bình 50° + tan70°/cot20°+2019cos bình 55°- cos bình 40°- tan49° 01/09/2021 Bởi Iris B= 2019 cos bình 35° + sin bình 50° + tan70°/cot20°+2019cos bình 55°- cos bình 40°- tan49°
= 2019 cos^2 35+ sin^2 50+ tan70/tan70 + 2019(1-sin^2 55)- sin^2 50 -tan 49 =2019(sin^2 55-sin^2 55 +1) +1 -tan 49 =2020-tan 49 Bình luận
= 2019 cos^2 35+ sin^2 50+ tan70/tan70 + 2019(1-sin^2 55)- sin^2 50 -tan 49
=2019(sin^2 55-sin^2 55 +1) +1 -tan 49
=2020-tan 49