1.(1—cos20° )除以（cos80° 乘s - 知识问答

1.(1—cos20° )除以（cos80° 乘sin20° )=根号二

1个回答

1、
左边=[1-(1-2sin²10)]/(sin10sin20)
=2sin²10/(sin10sin20)
=2sin10/sin20
=2sin10/2sin10cos10
=1/cos10
所以不等于根号2
2、
y=2(1+cos2x)/2+sin2x
=sin2x+cos2x+1
=√2(√2/2*sin2x+√2/2cos2x)+1
=√2(sin2xcosπ/4+cos2xsinπ/4)+1
=√2sin(2x+π/4)+1
-1

相关问题