Comments on: Angle No Enough! http://www.exampaper.com.sg/questions/e-maths/angle-no-enough Sassy O Level Maths Tuition, Questions & Tips from Singapore's Favourite Private Tutor Sun, 05 Feb 2012 17:08:39 +0000 hourly 1 By: Miss Loi http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11303 Miss Loi Sat, 02 Aug 2008 14:35:02 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11303 Correcto <b>Clarion</b>! <i>Steady Poon Pi Pi</i>!!! Since <a href="/tag/circular-measure" rel="nofollow">Circular Measure</a> has now made its way into the New Syllabus, E-Maths students now have to be careful to express your angle <var>θ</var> to <strong>RADIAN</strong> in your arc length and sector area formulae. On top of that, A-Maths students must remember to do likewise whenever you see range of angles like <span class="highlight">0 < <var>x</var> < 2<var>π</var></span> in any of your trigonometry questions! Correcto Clarion! Steady Poon Pi Pi!!!

Since Circular Measure has now made its way into the New Syllabus, E-Maths students now have to be careful to express your angle θ to RADIAN in your arc length and sector area formulae.

On top of that, A-Maths students must remember to do likewise whenever you see range of angles like 0 < x < 2π in any of your trigonometry questions!

]]> By: clarion-x http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11299 clarion-x Sat, 02 Aug 2008 12:16:06 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11299 I KNOW! radian mode is when calculating arc length and area of sector (when using s= r x θ for arc length and a= r<sup>2</sup> x θ/2 for area of sector) also for A Maths questions when range is given in terms of pi. Degrees mode for everything else. Am I right? I KNOW!

radian mode is when calculating arc length and area of sector (when using s= r x θ for arc length and a= r2 x θ/2 for area of sector)

also for A Maths questions when range is given in terms of pi.

Degrees mode for everything else.
Am I right?

]]> By: Miss Loi http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11271 Miss Loi Fri, 01 Aug 2008 17:15:29 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11271 <b>.I:</b> The angle of elevation is the angle above horizontal from a point <var>X</var> looking <em>upwards</em> towards another point <var>Y</var> that is higher. (What about the angle of <em>depression</em> then? :) ) So in our case we have 3 <em>lower</em> points <var>A</var>, <var>B</var> and <var>E</var> (from the workings in comment #7) looking upwards towards a common point <var>D</var>. However each of the points <var>A</var>, <var>B</var> and <var>E</var> has a <em>different</em> angle of elevation as their respective distances from <var>D</var> (or <var>C</var>) is different. So to summarize once more the angles of elevations obtained from the workings in Comment#7: ∠ of elevation from <var>A</var> = 38.1° ∠ of elevation from <var>B</var> = 29.1° ∠ of elevation from <var>E</var> = 42° One can safely assume that these angles are the max/min values since all other points between <var>A</var> & <var>E</var> & <var>B</var> would have angles that are < 42° and > 29.1° Where would you rather sit if you want your neck to bend upwards the least? Which is the worst spot where your neck needs to bend upwards the most? P.S. Not sure if Miss Loi understood the 2nd part of your question, but if you know your <i>TOA CAH SOH</i> the angle can still be found if you know the distance from <var>AB</var> to <var>D</var> (the hypotenuse) - but this will of course depend on what's given in the question. .I: The angle of elevation is the angle above horizontal from a point X looking upwards towards another point Y that is higher. (What about the angle of depression then? :) )

So in our case we have 3 lower points A, B and E (from the workings in comment #7) looking upwards towards a common point D.

However each of the points A, B and E has a different angle of elevation as their respective distances from D (or C) is different.

So to summarize once more the angles of elevations obtained from the workings in Comment#7:

∠ of elevation from A = 38.1°
∠ of elevation from B = 29.1°
∠ of elevation from E = 42°

One can safely assume that these angles are the max/min values since all other points between A & E & B would have angles that are < 42° and > 29.1°

Where would you rather sit if you want your neck to bend upwards the least?
Which is the worst spot where your neck needs to bend upwards the most?

P.S. Not sure if Miss Loi understood the 2nd part of your question, but if you know your TOA CAH SOH the angle can still be found if you know the distance from AB to D (the hypotenuse) - but this will of course depend on what's given in the question.

]]> By: .l http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11259 .l Fri, 01 Aug 2008 08:17:45 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11259 So is the worst seat possible at A? Seems that the angles of elevation also include the greatest one of 42 degrees. Does that mean if one is not allowed to find the distance between foot of x and A then the angle can't be used? .l So is the worst seat possible at A? Seems that the angles of elevation also include the greatest one of 42 degrees. Does that mean if one is not allowed to find the distance between foot of x and A then the angle can't be used?
.l

]]> By: Miss Loi http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11239 Miss Loi Thu, 31 Jul 2008 16:49:01 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11239 <b>rinaz:</b> A fellow Row 2-er? Ain't the view fantastic that night? Oh, and <strong class="highlight superbig">Happy Birthday Gal!</strong> And <b>Someone</b>, there's absolutely nothing to be embarrassed about. As the old adage goes: "It's better to have tried and pressed the calculator buttons wrongly then never tried at all"! ;) rinaz: A fellow Row 2-er? Ain't the view fantastic that night?

Oh, and

Happy Birthday Gal!

And Someone, there's absolutely nothing to be embarrassed about. As the old adage goes: "It's better to have tried and pressed the calculator buttons wrongly then never tried at all"! ;)

]]> By: Someone http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11228 Someone Thu, 31 Jul 2008 10:16:20 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11228 Yeah, I pressed the buttons wrongly. So embarrassing. Haha. Yeah, I pressed the buttons wrongly. So embarrassing. Haha.

]]> By: rinaz http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11225 rinaz Thu, 31 Jul 2008 09:30:37 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11225 Hmm ... I've got the feeling we were sitting in the same row Hmm ... I've got the feeling we were sitting in the same row

]]> By: Money No Enough 2 Gala Premiere 《钱不够用2》 | 新加坡部落格大奖 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11224 Money No Enough 2 Gala Premiere 《钱不够用2》 | 新加坡部落格大奖 Thu, 31 Jul 2008 09:25:54 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11224 [...] Miss Loi - Angle No Enough! [...] [...] Miss Loi - Angle No Enough! [...]

]]> By: Miss Loi http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11216 Miss Loi Thu, 31 Jul 2008 06:16:36 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11216 <b>Li-sa</b>: See Miss Loi's comments on your workings ;) <b>Someone:</b> Your error is in Part 2 (area of the Δ <var>ABC</var>) but your working's fine so it could be down to pushing the wrong buttons in your calculator. As you can see, in a multi-part question, an error in an earlier part can easily snowball into errors in later part of the question (i.e. Part 5) so please tread with care! <div class="attention highlight"> Though it's probably not related to your case, Miss Loi would like to take this opportunity to remind all students to make sure your calculator is set to <strong>DEGREE MODE</strong> (vs RADIAN) to avoid a repeat of the tragedies that have been afflicting many students. Do you know then, which kind of questions would require you to express your angles in RADIANS (e.g. <var>π</var>, <var>π</var>/2 etc.)? </div> And a nice touch for the <em>TOA CAH SOH</em> parts in your workings and for this question we can safely assume that the angles of elevation will never exceed 90°, else the screen will be on top and over everyone's head! This is not an Omnimax theatre! LOL Li-sa: See Miss Loi's comments on your workings ;)

Someone: Your error is in Part 2 (area of the Δ ABC) but your working's fine so it could be down to pushing the wrong buttons in your calculator.

As you can see, in a multi-part question, an error in an earlier part can easily snowball into errors in later part of the question (i.e. Part 5) so please tread with care!

Though it's probably not related to your case, Miss Loi would like to take this opportunity to remind all students to make sure your calculator is set to DEGREE MODE (vs RADIAN) to avoid a repeat of the tragedies that have been afflicting many students.

Do you know then, which kind of questions would require you to express your angles in RADIANS (e.g. π, π/2 etc.)?

And a nice touch for the TOA CAH SOH parts in your workings and for this question we can safely assume that the angles of elevation will never exceed 90°, else the screen will be on top and over everyone's head!

This is not an Omnimax theatre! LOL

]]> By: Someone http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11208 Someone Thu, 31 Jul 2008 00:17:38 +0000 http://www.exampaper.com.sg/questions/e-maths/angle-no-enough#comment-11208 It seems I made an error calculating something. =( It seems I made an error calculating something. =(

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