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Exam Questions HH]elp

I need some help with these exam questions. Struggling with the proof of trig identities.

Thanks. :smile:


https://www.dropbox.com/sh/q829c1wi86mazt7/AACHOgK4NIDFS-UWMwqF8Ra1a?dl=0
Original post by Jeevs090909
I need some help with these exam questions. Struggling with the proof of trig identities.

Thanks. :smile:
https://www.dropbox.com/sh/q829c1wi86mazt7/AACHOgK4NIDFS-UWMwqF8Ra1a?dl=0


cosec xsecx+2cot2xsinx+cosx\displaystyle \mathrm{cosec \ } x \equiv \sec x + \frac{2 \cot 2x}{\sin x + \cos x}

Start with the RHS. Express everything in terms of sin and cos, then get it under the same denominator.
Reply 2
Original post by RDKGames
cosec xsecx+2cot2xsinx+cosx\displaystyle \mathrm{cosec \ } x \equiv \sec x + \frac{2 \cot 2x}{\sin x + \cos x}

Start with the RHS. Express everything in terms of sin and cos, then get it under the same denominator.


Thanks :smile:
Original post by Jeevs090909
Thanks :smile:


For the circle question, you simply need to get it in the form (xa)2+(yb)2=r2(x-a)^2+(y-b)^2 = r^2 before you answer the questions. After you do that, part (a) is just to read off the centre. Then for part (b), you need to know that r2>0r^2 > 0 and hence whatever you end up with on the RHS in terms of kk, make that > 0 and hence deduce the inequality for kk
Original post by Jeevs090909
Thanks :smile:


For the other identity question, again, just express the LHS in terms of sines and cosines, get it under the same denominator, then spot the identity sin2θ=2cosθsinθ\sin 2\theta = 2 \cos \theta \sin \theta and use it before coming to a stop at the required result.
For part b, just set the RHS of the identity equal to 1 and observe further what happens why the equality yields no solutions.

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