\(A=sin^225+cos^2\left(90-65\right)-tan35+tan\left(90-55\right)-\frac{cot32}{cot\left(90-58\right)}\)

\(=sin^225+cos^225-tan35+tan35-\frac{cot32}{cot32}\)

\(=1-0-1=0\)

giúp mình đi!!

\(\sin^225^o+\sin^265^o-\tan35^o+\cot55^o-\frac{\cot32^o}{tan58^o}\)

\(=\cos^265^o+\sin^265^o-\cot55^{^{ }o}+\cot55^o-\frac{\tan58^o}{\tan58^o}\)

\(=1-0-1\)

\(=0\)

nhớ k cho mik nha ^^

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

\(=2\left(sin30^o-có60^o\right)+1\)

\(=2\left(sin30^o-sin30^o\right)+1=1\)

b) \(B=3sin^225^o+3sin^265^o-tan35^o+cot55^o-\frac{cot32^o}{tan58^o}\)

\(=3\left(sin^225^o+cos^225^o\right)-\left(tan35^o-cot55^o\right)-\frac{cot32^o}{cot32^o}\)

\(=3-\left(tan35^o-tan35^o\right)-1\)

\(=2\)

c) \(C=tan67^o-cos23^o+cos^216^p+cos^274^o-\frac{4cot37^o}{2tan53^o}\)

= \(tan67^o-tan67^o+sin^274^o+cos^274^o-\frac{4cot37^o}{2cot37^o}\)

\(=1-2=-1\)

d) \(D=2cot37^ocot53^o+sin^228^o-\frac{3tan54^o}{cot36^o}+sin^262^o\)

\(=2cot37^otan37^o+sin^228^o+cos^228^o-\frac{3tan54^o}{tan54^o}\)

\(=2+1-3=0\)

Mấy bài kiểu này bạn chỉ cần áp dụng tính chất tỉ số lượng giác của hai góc phụ nhau và các hệ thức trong bài tập số 14 (SGK - Tr.77) là sẽ ra thôi

Chúc bạn học tốt nhé!

a, \(\cos^215+\cos^225+\cos^235+\cos^245+\sin^235+\sin^225+\sin^215\)

=\(\left(\cos^215+\sin^215\right)+\left(\cos^225+\sin^225\right)+\left(\cos^235+\sin^235\right)+\cos^245\)

=\(1+1+1+\frac{1}{2}=\frac{7}{2}\)

b.\(\sin^210-\sin^220-\sin^230-\sin^240-\cos^240-\cos^220+\cos^210\)

=\(\left(\sin^210+\cos^210\right)-\left(\sin^220+\cos^220\right)-\left(\sin^240+\cos^240\right)-\sin^230\)

=\(1-1-1-\frac{1}{4}=-\frac{5}{4}\)

c,\(\sin15+\sin75-\sin75-\cos15+\sin30=\sin30=\frac{1}{2}\)

Ta có: \(A=\sin^25^0+\sin^225^0+\sin^245^0+\sin^265^0+\sin^285^0\)

\(=\left(\sin^25^0+\sin^285^0\right)+\left(\sin^225^0+\sin^265^0\right)+\dfrac{1}{2}\)

\(=2+\dfrac{1}{2}=\dfrac{5}{2}\)

\(\Rightarrow A=\left(sin^25^0+sin^285^0\right)+\left(sin^225^0+sin^265^0\right)+sin^245^0=\left(sin^25^0+cos^25^0\right)+\left(sin^225^0+cos^225^0\right)+\dfrac{1}{2}=1+1+\dfrac{1}{2}=\dfrac{5}{2}\)