化简sin^2(42°+b)-2tan(45°+b)tan(45°-b)+sin^2(48°-b)-cot^2(270°
化简sin^2(42°+b)-2tan(45°+b)tan(45°-b)+sin^2(48°-b)-cot^2(270°
化简sin^2(a+35°)+tan(315°-b)*cot(b+45°)+cos^2(145°-a)
tan[(A+B)/2]为什么可以化为cot(C/2)?A+B+C=180°
已知sin(2a+b)=3sin(b) 求tan(a+b)/tan(a)的值
已知0<A<45°,0<B<45°,3sinB=sin(2A+B),tan²(A/2)=1-4tan(A/2)
tan^2a =2tan^2b+1 求证 cos2a +sin^2b=0
已知tan(a+b)=2tan a 证明 3sinb=sin(2a+b)
a为二像限则角则必有A.tan a/2>cot a/2 B.tana/2cosa/2D.cos>sin
2(tan a+tan b)
已知tan^2A=2tan^B+1求证sin^2B=2sin^2A-1
已知sin^2B=2sin^2A-1求证tan^2A=2tan^B+1
已知tan^2 a=2tan^ B +1,求证sin^2 b=sin^2 a -1