若sin^2a
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若sin^2a
若sin^2a
若sin^2a
不等式两边同时加sin^2a可得:
sin^2a+sin^2a2sin^2a|sina|3π/4+2kπ
若sin^2a
1-sin a+sin a的平方-sin a的立方+……若a是正锐角,且sin a-cos a=0.5,求1-sin a+sin^2a-sin^3a+……
在三角形ABC中,若(a^2+b^2)sin(A-B)=(a^2-b^2)sin(A+B),则三角形是?a/sinA=b/sinB=k则a=ksinA,b=ksinB代入(a^2+b^2)sin(A-B)=(a^2-b^2)sinC并把k约分(sin²A+sin²B)sin(A-B)=(sin²A-sin²B)sin(A+B) sin²A*[sin(A+B)-sin(A-B)
若0〈a1 (2)sin a
若0〈a1(2)sin a
若sin(π+a)
sin^2(-a)化简
sin(arccos(2sin(a)))=
【证明】Sin A+sin B=2Sin 22
若sin a -cos a=-5/4. 则sin 2a 值为
急 sin^A=sin^B=sinC(sinB+sinC)三角形ABC中,若sin^A=sin^B=sinC(sinB+sinC),则角A=呃……是sin^2A=sin^2B+sinC(sinB+sinC)
在三角形ABC中,若sin^2A=sin^2B+sin^2C+sinBsinC,求A的值
在△ABC中,若sin^2A-sin^2B-sin^2C=sinBsinC,则∠A=
证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b,
求证:sin(a+b)sin(a-b)=sin^2a-sin^2b
sin a+sin 2a +sin 3a +...+sin na怎么求和?
sin a+sin 2a +sin 3a +...+sin na怎么求和?
若sin a cos a