Какие из равенств верны ?
а) sin40*=sin140*
b) cos140*= - cos40*
c) cos46*=cos134*
d) sin130*=sin50*
e) sin120*= - sin60*
f) cos150*= - cos30*
Ответы
Ответ дал:
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Формулы приведения:
![sin(180^circ- alpha )=sin alpha
\
cos(180^circ- alpha )=-cos alpha](https://tex.z-dn.net/?f=sin%28180%5Ecirc-+alpha+%29%3Dsin++alpha+%0A%5C%0Acos%28180%5Ecirc-+alpha+%29%3D-cos++alpha+ "sin(180^circ- alpha )=sin alpha
\
cos(180^circ- alpha )=-cos alpha")
![sin40^circ=sin140^circ
\
sin(180^circ-40^circ)=sin140^circ
\
sin140^circ=sin140^circ](https://tex.z-dn.net/?f=sin40%5Ecirc%3Dsin140%5Ecirc%0A%5C%0Asin%28180%5Ecirc-40%5Ecirc%29%3Dsin140%5Ecirc%0A%5C%0Asin140%5Ecirc%3Dsin140%5Ecirc "sin40^circ=sin140^circ
\
sin(180^circ-40^circ)=sin140^circ
\
sin140^circ=sin140^circ")
верно
![cos140^circ= - cos40^circ
\
-cos(180^circ-140^circ)= - cos40^circ
\
-cos40^circ= - cos40^circ](https://tex.z-dn.net/?f=cos140%5Ecirc%3D+-+cos40%5Ecirc%0A%5C%0A-cos%28180%5Ecirc-140%5Ecirc%29%3D+-+cos40%5Ecirc%0A%5C%0A-cos40%5Ecirc%3D+-+cos40%5Ecirc "cos140^circ= - cos40^circ
\
-cos(180^circ-140^circ)= - cos40^circ
\
-cos40^circ= - cos40^circ")
верно
![cos46^circ=cos134^circ
\
-cos(180^circ-46^circ)=cos134^circ
\
-cos134^circ=cos134^circ](https://tex.z-dn.net/?f=cos46%5Ecirc%3Dcos134%5Ecirc%0A%5C%0A-cos%28180%5Ecirc-46%5Ecirc%29%3Dcos134%5Ecirc%0A%5C%0A-cos134%5Ecirc%3Dcos134%5Ecirc "cos46^circ=cos134^circ
\
-cos(180^circ-46^circ)=cos134^circ
\
-cos134^circ=cos134^circ")
неверно
![sin130^circ=sin50^circ
\
sin(180^circ-130^circ)=sin50^circ
\
sin50^circ=sin50^circ](https://tex.z-dn.net/?f=sin130%5Ecirc%3Dsin50%5Ecirc%0A%5C%0Asin%28180%5Ecirc-130%5Ecirc%29%3Dsin50%5Ecirc%0A%5C%0Asin50%5Ecirc%3Dsin50%5Ecirc "sin130^circ=sin50^circ
\
sin(180^circ-130^circ)=sin50^circ
\
sin50^circ=sin50^circ")
верно
неверно
![cos150^circ= - cos30^circ
\
-cos(180^circ-150^circ)= - cos30^circ
\
-cos30^circ= - cos30^circ](https://tex.z-dn.net/?f=cos150%5Ecirc%3D+-+cos30%5Ecirc%0A%5C%0A-cos%28180%5Ecirc-150%5Ecirc%29%3D+-+cos30%5Ecirc%0A%5C%0A-cos30%5Ecirc%3D+-+cos30%5Ecirc "cos150^circ= - cos30^circ
\
-cos(180^circ-150^circ)= - cos30^circ
\
-cos30^circ= - cos30^circ")
верно
верно
верно
неверно
верно
неверно
верно
Ответ дал:
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Спасибо большое))
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