高中数学题求助,快~已知锐角三角
锐角三角形 ,p与q是共线向量
cosA+sinA）/(2-2sinA) =(1+sinA)/(sinA-cosA)
===>sin²A-cos²A=2(1-sin²A)
3sin²A-cos²A=2
3-4cos²A=2
cos²A=1/4 ==>A =π/3
2, C=2π/3 -B
y=2sin²B+cos[(C-3B)/2]
=2sin²B+cos[(π/3) -2B]
=(1-cos2B)+(1/2)cos2B +(√3)sin2B/2
=(√3)sin2B/2 -(1/2)cos2B +...全部
锐角三角形 ,p与q是共线向量
cosA+sinA）/(2-2sinA) =(1+sinA)/(sinA-cosA)
===>sin²A-cos²A=2(1-sin²A)
3sin²A-cos²A=2
3-4cos²A=2
cos²A=1/4 ==>A =π/3
2, C=2π/3 -B
y=2sin²B+cos[(C-3B)/2]
=2sin²B+cos[(π/3) -2B]
=(1-cos2B)+(1/2)cos2B +(√3)sin2B/2
=(√3)sin2B/2 -(1/2)cos2B +1
=sin(2B -π/6)
B∈(0,π/2)
2B∈(0,π)
sin(2B -π/6)取最大值1时,B=π/3
。
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