Question

求下列各式的值：1.sin630°+tan1125°+tan765°+cos540° 2.cos[(-23/3)π]+t

Answer 1

sin630°+tan1125°+tan765°+cos540°=sin-90°+tan45°+tan45°+cos180°=-1+1+1-1=0

cos[(-23/3)π]+tan[(17/4)π] =cosπ/3+tanπ/4=3/2

sinα=√ 3/4y=y/√(3+y^2),y=√(7/3),cosα=-√ 3/√(3+y^2)=3/4,tanα=√7/3