cos(a-π/6)+sina=4√3/5
cosa*cos(π/6)+sina*sin(π/6)+sina=4√3/5
(√3/2)*cosa+(3/2)*sina=4√3/5
√3*sin(a+π/6)=4√3/5
所以sin(a+π/6)=4/5
故sin(a+7π/6)=sin(a+π/6+π)=-sin(a+π/6)=-4/5
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已知cos(a-派/6)+sina=4/5根号3,则sin(a+7/6派)的值是?
cos(a-π/6)+sina=4√3/5
cosa*cos(π/6)+sina*sin(π/6)+sina=4√3/5
(√3/2)*cosa+(3/2)*sina=4√3/5
√3*sin(a+π/6)=4√3/5
所以sin(a+π/6)=4/5
故sin(a+7π/6)=sin(a+π/6+π)=-sin(a+π/6)=-4/5
如果不懂,请Hi我,祝学习愉快!