A-Level Edexcel C3 June 2010 Q7d : ExamSolutions

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[arbiterb]

Why don't we change limits in this question?
Surely 0 < t < 12 is not the same as saying: 0 < 4tpi/25 - 0.6435 < 12.

Confused.

[smartypants]

thank you for thiss.. i have been stuck on how to change the hours into minutes!!

[kurdishboy]

@MrCajogos because we are trying to find out second value as when we did Sin(0.4) you can straight away use the cast diagram because you have two points on the graph that have these points between 0 and 360

[ahmed]

thanks for all the efforts you make for us :) this is really very helping .

[VisualiseTheFun]

It seems that the main issue that most people, and certainly those in the comments section, have with this question is the limits to the answer. Therefore, an explanation would be most helpful.

[shararzaid]

The answer can be written in 2hr 6min ; 6hr 43min or 126 ; 403

[artisanone]

What I'm confused about is before it says T is within 0=<t<12, with that being the case wouldn't there be 3 answers? as T would be 2.0988, 6.71136 and also [2.0988 + 2pi] as it would be within those limits?? Im confused. :(

[cajogos]

why did we ignore, at 2:52, the 4pi(t)/25-0.64635? and only did the inverse sin of (0.4)?

[imandarwishh]

thank you so much for all your videos, i'd be getting 0/75 without them! I was just wondering though, there was a similar question to this in the jan09 paper, the last question in that paper. But in that question they simply did (#t - a) =180 .. they didn't keep the sin or +6 as done in this question? So how do I know which way to do it?

[shizzlers]

Why do we not have to change the limits on this question, I thought on all CAST questions we have to? Because if we change the limits the second solution is too large? Thanks

[heynub]

How did you know there were two solutions to t?