化简[(cos^2a-sin^2B)/(sin^2a*cos^2B)]-cot^2a*cot^2B
化简sin^2(a+35°)+tan(315°-b)*cot(b+45°)+cos^2(145°-a)
a为二像限则角则必有A.tan a/2>cot a/2 B.tana/2cosa/2D.cos>sin
化简:sin(a-π)cot(a-2π)/cos(a-π)tan(a-2π)
化简 (sin^2(a+π)cos(2π-a)cot(a-2π))/(tan(π-a)cos^3(-a-π))
化简 cot(a+4π)cos(a+π)[sin(a+3π)]^2/tan(π+a)[cos(-π-a)]^2
求证:(2-cos²a)(1+2cot²a)=(2+cot²a)(2-sin²a
[sin(A-派)cot(A-2派)]/[cos(A-派)tan(A-2派)]
若sin a+cos a=2,则tan a+cot a=
化简[sin(2A+B)]/sinA-2cos(A+B)
cos(a+b)=-1,tan a =2 cot b=?
若cos(a+b)=-1,tan a=2,求cot b的值
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a