已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围
人气：373 ℃ 时间：2020-05-09 04:12:43
解答
3(sinA)^2+2(sinB)^2=5sinA(sinA)^2+(sinB)^2=5sinA/2-(sinA)^2/25sinA/2-(sinA)^2/2=-(1/2)(sinA-5/2)^2+25/4sinA=-1 5sinA/2-(sinA)^2/2=-49/8+25/4=1/8sinA=1 5sinA/2-(sinA)^2/2=-9/8+25/4=41/81/8 ≤ (sinA)^2+...
推荐
猜你喜欢
