Question

问高一数学题(要有解说的）1、sin22.5= cos22.5= tan22.5=2、sin(-7π/12)= cos(

Answer 1

1.sin22.5=sin(45/2)同理,后面也用半角公式

2.sin(-7π/12)=-sin(7π/12)=-sin(π/4+π/3)

由上,只要化成特殊角即可