比大小,sin(-110°)与sin(-820°)
问题描述：
比大小,sin(-110°)与sin(-820°)
答
sin(-110°)=-sin(70°)
sin(-820°)=sin(-100°)=-sin(80°)
∵sin(70°)＜sin(80°)
∴-sin(70°)＞-sin(80°)
∴sin(-110°)＞sin(-820°)
答
sin(-110°)大,sin(-820°)小.
sin(-820°)可化简为sin(-100°),-820°+720°=-100°
sin(-110°)等同于sin(250°),sin(-100°)等同于sin(260°),同在第三区间,而第三区间是递减区间,所以前者打后者小!
也可根据sin曲线图来判断更简单!