Question

1.   determine o valor da expressão abaixo.

Answer 1

                                           $B=\dfrac{\sec x \cdot \cot x}{\csc(-x)\cdot \cot(-x)\cdot \cos x}\\ \\ \\ B=\dfrac{\csc x}{\csc x\cdot \cot x\cdot \cos x}\\ \\ \\ B=\dfrac{1}{\cot x\cdot \cos x}\\ \\ \\ B=\dfrac{\sin x}{ \cos^2 x}\\ \\ \\ B=\dfrac{\sin x}{1- \sin^2 x}\\ \\ \\ B=\dfrac{\sqrt{2}-1}{1- (\sqrt{2}-1)^2 }\\ \\ \\ B=\dfrac{\sqrt{2}-1}{2\sqrt{2}-2 }\\ \\ \\ \boxed{B=\dfrac{1}{2}}$