Trigonometry : Solving Equations using identities (Example 2) : ExamSolutions

[xImMorTalxT]

@ExamSolutions i worked this all out by myself before watching your working out, and i got everything correct up to the final part. I got -60 and 60 deg, but i also got -90 and 90., because COS graph crosses x asis at 90 and 270 deg, so 90 is within the 180 degrees limit, so wouldn't the final solutions be -90,-60,60,90 ?? Sorry if i've made a stupid mistake.

P.S great vids, i didn't know anything about trig identities 20 mins ago and now i'm attempting this sort of question because of you :)

[ExamSolutions]

@xImMorTalxT The cos graph does cross at 90, -90, 270 and -270 but this is when cos x = 0. In this example cos x = 1 though.

[xImMorTalxT]

@ExamSolutions oh my god i'm such an idiot haha stupid mistake. don't know why i thought it was 0 when question clearly gives =1 :)

[focuseduntilsuccessf]

are you able to ever divide during trigonometric equations? my teacher told me not to, but it's nearly impossible if you do not. Is he confusing the work with identities?

[Neworleanz365]

Would you get the same answer's if you converted the (3-3cos theta) as sin theta as the subject?

[ExamSolutions]

@Neworleanz365 Of course but I would not recommend it. How are you going to change (3 - 3cos theta) int a function in terms of sin theta? Much easier to do it the way I did it.

[Neworleanz365]

@ExamSolutions No i was just wondering, thanks tho i'll bear that in mind :)

[lhsom93]

Thank you so much ExamSolutions! You are a life saver! Math is anyway tough if you got nutty tutors....but you make up for all that! Simply outstanding! Great work! What we find difficult or even what seem impossible to understand in the classroom is so well explained that you just can't help but master all of it! Once again thanks a lot!

[ExamSolutions]

@lhsom93 Thank you for your support and comment.

[Anar2388]

simply awesome:)

[ivanina2011]

sorry my bad c2 not c1, i tried looking for it but unfortunately i couldn't find it

[ivanina2011]

edexcel

[ExamSolutions]

@ivanina2011 Do you not mean C2 Edexcel? Have you looked on my site under C2 Edexcel as I have done a number of videos for this.

[ivanina2011]

Hi my name is Eva and I am an A level Maths student, i saw your videos and they are so easy to understand, can u please upload more on trigonometric identities and simple equations ( that's from c1 chapter 10), i would really appreciated, thank u :)

[ExamSolutions]

@ivanina2011 What board are you following?

[JaZzYSkIlLz94]

thankyou so much, going to utilise this to pass my Additional Maths :L

[ExamSolutions]

@JaZzYSkIlLz94 Thanks - Hope you pass your Add Maths now.