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Author Topic: C3 Trigonometry help!  (Read 705 times)

Offline IO4567

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C3 Trigonometry help!
« on: February 10, 2010, 03:54:44 pm »
Please could someone help me with this question... I've been at it for ages

Find, to 1 decimal place, the values of x , 0? x ? 360ยบ, which satisfy the equation

2sinx = cos(x - 60)

Thank you!
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Offline astarmathsandphysics

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Re: C3 Trigonometry help!
« Reply #1 on: February 10, 2010, 07:03:26 pm »
2sinx = cos(x - 60)
2sinx=cosxcos60+sinxsin60
2sinx=1/2cosx+sqrt(3)/2 sinx
group the sinx terms
sinx(2-sqrt(3) /2)=1/2cosx
divide by cosx to get tanx=(1/2)/(2-sqrt(3) /2) so x=23.8 degress and 180+23.9=203.9
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