向右平移变成:y=sin[2(x-3π/8)+ π/4]=sin(2x- π/2)
横坐标再缩短1/2变成:y=sin(4x-π/2)
根据sine rule:a/sinA =b/sinB =c/sinC记为①
a/cosA =b/COSB =c/COSC 记为②
②/①得:sinA/cosA =sinB/COSB =sinC/COSC ,化简得tanA=tanB=tanC
又因为A、B、C都是三角形内角,所以A=B=C=π/3,三角形是正三角形
向右平移变成:y=sin[2(x-3π/8)+ π/4]=sin(2x- π/2)
横坐标再缩短1/2变成:y=sin(4x-π/2)
根据sine rule:a/sinA =b/sinB =c/sinC记为①
a/cosA =b/COSB =c/COSC 记为②
②/①得:sinA/cosA =sinB/COSB =sinC/COSC ,化简得tanA=tanB=tanC
又因为A、B、C都是三角形内角,所以A=B=C=π/3,三角形是正三角形