Bài 7: Tính

a/ \(A=2sin30^o-2cos60^o+tan45^0\)

b/ \(B=3sin^225^o+3sin^265^o-tan35^o+cotag55^o-\frac{cos32^o}{tan58^o}\)

c/ \(C=tan67^o-cotag23^o+cos^216^o+cos^274^o-\frac{4cotag37^o}{2tan53^o}\)

d/ \(D=2cotag37^ocotag53^o+sin^228^o-\frac{3tan54^o}{cotag36^o}+sin^262^o\)

e/ \(L=\left(sin1^o+sin2^o+....+sin88^o+sin89^o\right)-\left(cos1^o+cos2^o+cos3^o+....+cos88^o+cos89^o\right)\)

f/ \(M=tan1^o.tan2^o.tan3^o.....tan88^o.tan89^o\)

Thực hiện phép tính

a) \(\tan40^o.\cot40^o+\frac{\sin50^o}{\cos40^o}\)

b) \(\cot44^o.\cot45^o.\cot46^o\)

c)\(\left(1+\tan^225^o\right).\sin^265^o\)

d) \(\tan35^o.\tan40^o.\tan45^o.\tan50^o.\tan55^o\)

e) \(\cos^220^o+\cos^240^o+\cos^250^o+\cos^270^o\)

f) \(\sin^227^o+\cos^227^o+\tan27^o-\cot73^o\)

bài 1 : không dùng bảng số hoặc máy tính, hãy tính :

a, A = \(\cos^220^o+\cos^230^o+\cos^240^o+.....+\cos^270^o\)

b, B = \(\sin^25^o+\sin^225^o+\sin^245^o+\sin^265^o+\sin^285^o\)

c, C = \(\sin^210^o-\sin^220^o+\sin^230^o-\sin^240^o-\sin^250^o-\sin^270^o+\sin^280^o\)

bài 2 : cho tam giác ABC vuông tại A, biết sin B = \(\frac{1}{4}\) C. Tính C ?