Question

Calcule usando arcos côngruos:
a) cos 9π/4
b)cos(-330)
c)cos 9π/2
d)cos 1140
e)cos 25π/6
f)cos (-15π/4)
g)cos11π
h)cos 570

Answer 1

a) cos 9π/4 = cos(8π/2 + π/4) = cos π/4 = √2/2
b) cos(-330°) = cos330° = cos(360° - 330°) = cos30° = √3/2
c) cos9π/2 = cos (8π/2 + π/2) = cosπ/2 = 0
d) cos1140° = cos(3 x360° + 60°) = cos60° = 1/2