常见的特殊角的三角函数值

可利用直角三形和正余弦函数图象得出：
sin 0° = 0
cos 0° = 1
tan 0° = 0
sin 30° = 1/2
cos 30° = √3/2
tan 30° = √3/3
sin 45° = √2/2
cos 45° = √2/2
tan 45° = 1
sin 60° = √3/2
cos 60° = 1/2
tan 60° = √3
sin 90° = 1
cos 90° = 0
sin37=3/5
cos37=4/5
tan37=3/4