满足sinπ∕5sinⅩ﹢cos4/5πcosⅩ=1∕2的锐角Ⅹ为多少?A.π∕6 B.7π∕15 C,π∕3 D.2π
若a是锐角,且满足sin(a-π/6)=1/3,则cos a 的值为多少?
a为锐角 cos(a+π/6)=4/5 求sin(2a+π/12)
求正确答案和解析.已知A为锐角,且2tan(π-A)-3cos(π/2+B)+5=0,tan(π+A)+6sin(π+B
三角函数:设a为锐角,若cos(a+π/6)=4/5,则sin(2a+π/12)的值为多少?
设a为锐角,若cos(a+π/6)=4/5,则sin(2a+π/12)的值为多少?
若a是锐角,且满足sin(a-π/6)=1/3,则sina 的值为多少?
已知a、b为锐角,a+b≠π/2,且满足3sinb=sin(2a+b)
已知α∈(π/2,π),且sinα=3/5,则sin^2α/2+(sin4αcos2α)/(1+cos4α)的值为多
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设a为锐角,若cos(a+π/6)=3/5,则sin(a-π/12)=
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设a为锐角,若cos(a+π/6)=4/5,则sin(2a+π/12)的值为?