Câu 1: Chứng minh đẳng thức:
a)frac{sin a}{1+cos a}frac{1-cos a}{sin a}
b)frac{cos a}{1-sin a}frac{1+sin a}{cos a}
c)frac{cos a}{1+sin a}+tan afrac{1}{cos a}
d) frac{sin a}{1+cos a}+frac{1+cos a}{sin a}frac{2}{sin a}
e) sin^4x+cos^4x1-2sin^2xcos^2x
f) sin^4x-cos^4x1-2cos^2x
g) sin^6x+cos^6x1-3sin^2xcos^2x
h) tan xtan yleft(cot x+cot yright)tan x+tan y
Đọc tiếp
Câu 1: Chứng minh đẳng thức:
a)\(\frac{\sin a}{1+\cos a}\)=\(\frac{1-\cos a}{\sin a}\)
b)\(\frac{\cos a}{1-\sin a}\)=\(\frac{1+\sin a}{\cos a}\)
c)\(\frac{\cos a}{1+\sin a}\)+\(\tan a\)=\(\frac{1}{\cos a}\)
d) \(\frac{\sin a}{1+\cos a}\)+\(\frac{1+\cos a}{\sin a}\)=\(\frac{2}{\sin a}\)
e) \(\sin^4x+\cos^4x\)=\(1-2\sin^2x\cos^2\)x
f) \(\sin^4x-\cos^4x\)=\(1-2\cos^2x\)
g) \(\sin^6x+\cos^6x\)=\(1-3\sin^2x\cos^2x\)
h) \(\tan x\tan y\left(\cot x+\cot y\right)\)=\(\tan x+\tan y\)
