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anonymous
 one year ago
Help with identities:
1. ( sin2x/sin x)(cos2x/cos x)=sec
2. (cos x+cos y)^2 +(sin xsin y)^2 =2+2cos(x+y)
anonymous
 one year ago
Help with identities: 1. ( sin2x/sin x)(cos2x/cos x)=sec 2. (cos x+cos y)^2 +(sin xsin y)^2 =2+2cos(x+y)

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0For question 1. it says the steps should be: apply the doubleangle formulas for sine and cosine, then simplify the expression. I got this far. \[(2\sin x \cos x)/\sin x)(2 \cos^2x1)/\cos x)\] \[2 \cos x=(2 \cos^2 x1)/\cos x\]

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1i don't think i am reading question 1. properly, can you type out the equation again (or draw it) please?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[\frac{ \sin (2x) }{ sinx }\frac{ \cos(2x) }{ \cos x }=\sec x\]

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1ah, i can read it properly now, thakyou

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1your working so far it good

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1you have \[LHS = 2 \cos x\frac{2 \cos^2 x1}{\cos x}\]

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1now break up the fraction like this \[\frac{a+b}{c}=\frac ac+\frac bc\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[\frac{ 2\cos^2 }{ \cos }=2 \cos\] \[\frac{ 1 }{ \cos}=\sec\] Is this right?

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1right!, (becareful with the extra sign, outside of the big fraction)

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1so you've got \[LHS = 2\cos x\frac{2 \cos^2 x1}{\cos x}\\ \qquad=2\cos x\left(\frac{2 \cos^2 x}{\cos x}+\frac{1}{\cos x}\right)\\ \qquad=2\cos x\left(2\cos x\sec x\right)\\\qquad=\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.02 cos x2cos x=0 sec x=sec x ?

UnkleRhaukus
 one year ago
Best ResponseYou've already chosen the best response.1be CAREFUL with the minus signs. \[\qquad=2\cos x\left(2\cos x\sec x\right)\\\qquad=2\cos x2\cos x+\sec x\\\qquad=\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ahhhh okay, I got it now!
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