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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: kettles on February 21, 2012, 06:39:09 pm

Title: how to find sin pi/8, cos pi/8 and tan pi/8
Post by: kettles on February 21, 2012, 06:39:09 pm

as the title says, how would i find their values !

Title: Re: how to find sin pi/8, cos pi/8 and tan pi/8
Post by: pi on February 21, 2012, 06:48:10 pm

You will have to use sin(2x), cos(2x), etc. formulas, letting pi/4 = 2x (so you solve for sin(x), cos(x), whatever; where x = pi/8) :D

Title: Re: how to find sin pi/8, cos pi/8 and tan pi/8
Post by: Special At Specialist on February 21, 2012, 06:59:37 pm

Yeah what pi said.

How you can tell is by converting to degrees. If it's divisible by 15 degrees, then you can use the addition/subtraction formulas. Otherwise, you need to use the double angle formulas.
In this case, pi/8 = 22.5 degrees, so the only option is to use the double angle formulas.

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