Trigonometry 2020 Q5 Paper 2 Leaving Cert Ordinary Level Maths

[@e.k5855]

21:19 why did I get a different figure on my calculator? I didn’t put it in wrong but I got 3835.173414

[@evamurphy2910]

any chance your calculator was in Radian mode instead of degrees?

[@itzkemm]

Thanks

[@blorgustoe6141]

We are being taught a different way of doing it,I tried it the way we are getting taught and I didn't get the same answer as you in question a.we do Sin55 over 1 = x over 100.Then we do 100Sin55 and put that in the calculator .Your answer seems right because it's 120 metres

[@evamurphy2910]

That sounds like you are using the Sine Rule. (Sin 90 = 1 - thats where the 1 comes from). But you have angles over angles, and sides over sides. Whereas you should have an angle and side = an angle and side. e.g. using your numbers: I would have 100/Sin55 = x/Sin90

[@gerryfleming8318]

No reason to use cosine on last one

[@evamurphy2910]

what you thinking Gerry?

[@gerryfleming8318]

@@evamurphy2910 I just used tan on both angles then added them , would they want you to use cosine in an exam or would it matter?

[@evamurphy2910]

@@gerryfleming8318 In general, it shouldn't matter how you do it, as long as the methods give the same answer. We all see it differently, and can only work it out that way. And there are many times there is more than 1 way to do things. When you get the tan here, you effectively get the length of the bottom. So you are assuming that the bottom is the same length as d. If the two banks are not parallel, then do you think the lengths could be slightly different?