I'm doing a review for my math class and came upon some that I cannot figure out.I don't know why I cannot get the right answer. I know all the rules, I've had tests on this stuff and received A's but these are different for some reason and I don't know why. If anyone can do even one of them I would so greatly appreciate it! my exam is tomarrow thanks(adsbygoogle = window.adsbygoogle || []).push({});

let sin(x)=5/13, cos(x)=12/13, sin(y)=4/5 and y is in Quadrant II and 0<or=to x <2pi

81. sin(x-y)=____

83. sin 2x =___

84. sin x/2 =___

now the rules above don't apply to these below

85. sin(pheta)=2/3 and 0<pheta<90 then cos2(pheta)=___

86.sin(2cos^-1(1/4))=___

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# Sin,cos problems

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