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Mathematics Question Thread
RuiAce:
--- Quote from: amandali on February 27, 2016, 08:10:47 am ---cos(2x+pie/6)=1/root2 -pie<=x<=pie
how do i find the angles in a simple way without getting the angles confused?
--- End quote ---
Edit: Holy crap the mistakes.
Phillorsm:
Thank you Jake and HPL, I really value all your help and time you spend here sharing your wisdom. HPL, what you said about not coming first giving you the motivation to work harder for the following exams was especially helpful :) Thanks again guys, now I need to get stuck into hardcore study mode for an ext1 exam on wednesday. Binomial, inverse, induction and harder 2u... Wish me luck! ;D
amandali:
how do you do this ques thanks ;D
a man in a rowing boat is presently 6km from the nearest point A on the shore. He wants to reach as soon as possible a point B that is further 20km down the shore from A. If he can row at 8km/hr and run at 10km/hr , how far from A should he land? ans: 8km
RuiAce:
--- Quote from: amandali on February 27, 2016, 07:55:06 pm ---how do you do this ques thanks ;D
a man in a rowing boat is presently 6km from the nearest point A on the shore. He wants to reach as soon as possible a point B that is further 20km down the shore from A. If he can row at 8km/hr and run at 10km/hr , how far from A should he land? ans: 8km
--- End quote ---
Weakly lacking information. There are three cases:
1. We want to minimise the time of the entire journey (this sounds extremely preferable to the others)
2. We want to minimise the distance of the entire journey (sounds very unfeasible as there is actually a very obvious answer)
3. We want to minimise only a part of the journey (e.g. reduce some walking
If the earlier answer didn't make sense, all the hints were given.
a) Rewrite boundaries because otherwise you don't know what you're trying to get at
b) Always use ASTC
c) Negative angles work in reverse (clockwise around ASTC)
Exact values are different. Use the formula sheet for exact values.
jakesilove:
--- Quote from: amandali on February 27, 2016, 07:55:06 pm ---how do you do this ques thanks ;D
a man in a rowing boat is presently 6km from the nearest point A on the shore. He wants to reach as soon as possible a point B that is further 20km down the shore from A. If he can row at 8km/hr and run at 10km/hr , how far from A should he land? ans: 8km
--- End quote ---
Hey!
This was actually quite a difficult question! First, you need to construct the relevant equation. Then, the differentiation part is quite tricky for a 2U question. Finally, even solving the equation is a bit of work! Below is my answer, I hope you find it helpful! In the case of questions like this, just think through what is actually happening in the example. Then, always create some sort of equation that you can differentiate!
Jake
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