已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/04/30 00:46:44
已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围
3(sinA)^2+2(sinB)^2=5sinA
(sinA)^2+(sinB)^2=5sinA/2-(sinA)^2/2
5sinA/2-(sinA)^2/2=-(1/2)(sinA-5/2)^2+25/4
sinA=-1 5sinA/2-(sinA)^2/2=-49/8+25/4=1/8
sinA=1 5sinA/2-(sinA)^2/2=-9/8+25/4=41/8
1/8 ≤ (sinA)^2+(sinB)^2 ≤ 41/8
(sinA)^2+(sinB)^2=5sinA/2-(sinA)^2/2
5sinA/2-(sinA)^2/2=-(1/2)(sinA-5/2)^2+25/4
sinA=-1 5sinA/2-(sinA)^2/2=-49/8+25/4=1/8
sinA=1 5sinA/2-(sinA)^2/2=-9/8+25/4=41/8
1/8 ≤ (sinA)^2+(sinB)^2 ≤ 41/8
已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围
关于三角函数的问题 已知3sin^2a+2sin^b=2sina,求sin^2a+sin^b的取值范围
【证明】Sin A+sin B=2Sin 22
证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b,
在三角形ABC中.已知sin^2A+sin^2B*sin^2C=sinB*sinC+sinC*sinA+sinA*sin
a,b为锐角,3sina+3sinb=1 ,3sin(2a)-2sin(2b)=0 求sin(a+2b)
为什么sin(a+b)-sina=2sin(b/2)cos(a+b/2)
证明三角函数等式sin(A+B)-sinA=2cos(A+B/2)sin(B/2)
已知sinA=sin(2A+B),求tan(2A+B)
已知sina=2/3,cosb=-3/4,且a,b都是第二象限角,求sin(a+b),sin(a-b)的值
已知sina=2/3,cosb=-1/4,a b为相邻象限的角,求sin(a=b)与sin(a-b)的值
已知sina+cosb=1/2,cosa+sinb=3/4,求sin(a+b)