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# Maths Core 3 - need help watch

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1. Need help with part a of this c3 maths question, can't seem to get it
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2. (Original post by Tcastle97)
Need help with part a of this c3 maths question, can't seem to get it
Turn the 2cosec2A into 2/sin2A and the cotA into cosA/SinA. Then convert the 2/2Sin2A into 2/2SinACosA (because Sin2A = 2SinACosA). Cancel the 2's as you will have 2/2SinACosA, so that become 1 / SinACosA. Then you want to have a common denominator so you multiply (top and bottom) of the cosA/SinA by cosA so that you have a common denominator of SinACosA. Then you put the fractions together and you get 1-cos^2A (because CosA*CosA = cos^2A) / SinACosA. 1 - Cos^2A is the same as Sin^2A so change the top to that. Then divide top and bottom by SinA. The top will become SinA and the bottom will become Cos A (because SinACosA divided by SinA = CosA as the SinA divided by SinA = 1 so you have 1*CosA which is just CosA. Then you have SinA / CosA which is the same as tanA. Hope that helps.
3. (Original post by OrionMusicNet)
Turn the 2cosec2A into 2/sin2A and the cotA into cosA/SinA. Then convert the 2/2Sin2A into 2/2SinACosA (because Sin2A = 2SinACosA). Cancel the 2's as you will have 2/2SinACosA, so that become 1 / SinACosA. Then you want to have a common denominator so you multiply (top and bottom) of the cosA/SinA by cosA so that you have a common denominator of SinACosA. Then you put the fractions together and you get 1-cos^2A (because CosA*CosA = cos^2A) / SinACosA. 1 - Cos^2A is the same as Sin^2A so change the top to that. Then divide top and bottom by SinA. The top will become SinA and the bottom will become Cos A (because SinACosA divided by SinA = CosA as the SinA divided by SinA = 1 so you have 1*CosA which is just CosA. Then you have SinA / CosA which is the same as tanA. Hope that helps.
Yeah that worked, thank you very much!

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