证明-csc^2(x)=(sec(x))/(2sin(x))

解答

证明

- csc^{2} (x) = \frac{sec ( x )}{2 sin ( x )}

假

求解步骤

- csc^{2} (x) = \frac{sec ( x )}{2 sin ( x )}

两侧不相等

对于

- csc^{2} (x) = \frac{sec ( x )}{2 sin ( x )}

代入

x = 1

- csc^{2} (1) = - 1.41228 \dots

- csc^{2} (1)

整理为小数形式

= - 1.41228 \dots

\frac{sec ( 1 )}{2 sin ( 1 )} = 1.09975 \dots

\frac{sec ( 1 )}{2 sin ( 1 )}

整理为小数形式

= 1.09975 \dots

两侧不相等

\Rightarrow 假

p ro v e \frac{sec ( x ) cos ( x )}{cot ( x )} = tan (x)

p ro v e 2 sin^{2} (\frac{9 θ}{2}) = 1 - cos (9 θ)

p ro v e cos (x) cos (x) = cos^{2} (x)

p ro v e 81 - 9 (3 sin (x))^{2} = - 1

p ro v e csc (x) + 1 = \frac{2}{sin ( x )}