Question

Calcule A sabendo que A= sen 3x +cos 4x - tg 2x, para x=π/2

Answer 1

Vamos là:

A = sen(3x) + cos(4x) - 2tg(2x)

x = π/2

sen(3π/2) = sen(270) = -1

cos(2π) = cos(360) = 1

tg(π) = 0

A = -1 + 1 - 0 = 0

Answer 2

Siga a resolução da questão

$\mathtt{A = \sin\left(3 \times \frac{\pi}{2} \right) + \cos\left(\cancel{4} \times \frac{\pi}{\cancel{2}} \right) - \tan\left(\cancel{2} \times \frac{\pi}{\cancel{2}} \right)} \\ \\ \mathtt{A = \sin\left(3 \times \frac{\pi}{2} \right) + \cos \left(2\pi \right) - \tan\left(\pi \right) } \\ \\ \mathtt{A = \sin\left( \frac{3\pi}{2} \right) + \cos\left(2\pi \right) - \tan\left( \pi\right)} \\ \\ \mathtt{A = - 1 + \cos\left( 2\pi\right) - \tan\left(\pi \right)} \\ \\ \mathtt{A = - 1 + 1 - \tan\left(\pi \right) } \\ \\ \mathtt{A =\cancel{ - 1} \cancel{ + 1} - 0} \\ \\\mathtt{A = - 0} \\ \\ \boxed{\mathtt{\therefore \: \: \: A = 0}}$

Resposta: A = 0

Att: José Armando