Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
c: \(\cot50^0>\cos50^0>\cos70^0\)
a: \(\tan40^0>\cos40^0>\cos60^0\)
b: \(\cot70^0=\tan20^0>\sin20^0>\sin10^0\)
a: \(A=\left(\sin^210^0+\sin^280^0\right)+\left(\sin^220^0+\sin^270^0\right)+...+\left(\sin^240^0+\sin^250^0\right)\)
=1+1+1+1
=4
b: \(B=\left(\cos^215^0+\cos^275^0\right)+\left(\cos^225^0+\cos^265^0\right)+...+\cos^245^0\)
\(=1+1+1+1+\dfrac{1}{2}=\dfrac{9}{2}\)
a: \(=\left(\cos^215^0+\cos^275^0\right)+\left(\cos^225^0+\cos^265^0\right)+\left(\cos^235^0+\cos^255^0\right)+\cos^245^0\)
=1+1+1+1/2
=3,5
b: \(=\left(\sin^210^0+\sin^280^0\right)-\left(\sin^220^0+\sin^270^0\right)+\left(\sin^230^0\right)-\left(\sin^240^0+\sin^250^0\right)\)
=1-1-1+1/4
=-1+1/4=-3/4
c: \(=\left(\sin15^0-\cos75^0\right)+\left(\sin75^0-\cos15^0\right)+\sin30^0\)
=1/2
A= sin275 + sin215 - cos250 - cos240 + cot40 . cot50
A= sin275 + cos275 - cos250 - sin250 + cot40 . tan40
A= (sin275 + cos275 )-(cos250 + sin250 ) +1
A= 1-1+1
A=1
\(A=\sin^275+\sin^215-\cos^250-\cos^240+\cot40.\cot50\)
\(A=\sin^275+\cos^275-\cos^250-\sin^250+\cot40.\tan40\)
\(A=1-1+1\)
\(A=1\)