1/cos50度+tan10度=?

来源:学生作业帮助网 编辑:作业帮 时间:2018/12/15 01:13:31
1/cos50度+tan10度=?1/cos50度+tan10度=?1/cos50度+tan10度=?=1/cos50°+sin10°/cos10°=1/sin40°+cos80°/sin80°=2c

1/cos50度+tan10度=?
1/cos50度+tan10度=?

1/cos50度+tan10度=?
=1/cos50°+sin10°/cos10°
=1/sin40°+cos80°/sin80°
=2cos40°/(2sin40°cos40°)+cos80°/sin80°
=(2cos40°+cos80°)/sin80°
=【2cos(10°+30°)+cos80°】/sin80°
=(2cos10°cos30°-2sin10sin30°+cos80°)/sin80°
=(2cos30°cos10°-sin10°+cos80°)/sin80°
=2cos30°cos10°/sin80°
=2cos30°
=√3
ps:如果你学过和差化积公式,能更简捷

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