化简√(1-sin20°cos20°)/√(1-cos^220°-cos20°)1.化简（√1-sin20°cos20°）/[（√1-cos^220°）-cos20°]2.若(2-5cos^2α)/（cos^2α-sin^2α）=-4，则tan=3.若(4sinα-2cosα)/(5cosα+3sinα)=6/11，则sin^4α-cos^4α=

Question

化简√(1-sin20°cos20°)/√(1-cos^2 20°-cos20°)
1.化简（√1-sin20°cos20°）/[（√1-cos^2 20°）-cos20°]
2.若(2-5cos^2α)/（cos^2α-sin^2α）=-4，则tan=
3.若(4sinα-2cosα)/(5cosα+3sinα) =6/11，则sin^4 α-cos^4 α=

Answer 1

1.化简[√(1-2sin20°cos20°)]/[√(1-cos² 20°)-cos20°]【原题的分子上可能少写了个2倍】原式=[√(cos20°-sin20°)²]/(sin20°-cos20°)=(cos20°-sin20°)/(cos20°-sin20°)=12.若(2-5cos²α)/...