Question

O valor da expressão sen 7pi/6 - 5 cos 2pi/3 é:
a)- 1
b)- 2
c)- 3
d)- 4
e)- 5

Answer 1

$seno \: \frac{7\pi}{6} - 5 \: cos \: \frac{2\pi}{3} \\ \\ \frac{7\pi}{6} = \frac{7(180)}{6} = \frac{1260}{6} = 210 \\ \frac{2\pi}{3} = \frac{2(180)}{3} = \frac{360}{3} = 120 \\ \\ (sen 210) - 5(cos120) \\ ( - sen30) - 5( - cos60) \\ (- \frac{1}{2}) - 5( - \frac{1}{2}) \\ - \frac{1}{2} + \frac{5}{2} \\ \frac{4}{2} = 2$
letra B