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C4 help

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Reply 1
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Qer
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Capture.PNG

need help in part b and d (i have no idea how to start working)

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In this question, i need help in last part
they have given domain so I thought that to get the range I just have to put 0 and 5 in the g(x)
and I got a range of g(x) any value less than or equal to 0 and 10 but the correst answer is
any value less than or equal to -2.25 and 10
Capture.1.PNG21.8KB
Reply 2
Avatar for Psst.
Psst.
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The funny thing is I got an A* in mathematics 6 months ago but I can't even remember how to do this
for 7 d

g(x) is a parabola which will have a lowest point. suppose this has y coordinate -7 then the range of the function would be y ≥ -7

so you need to find the lowest point/ vertex/ turning point :h:
Original post by Qer


need help in part b and d (i have no idea how to start working)


Consider the fact that the vertical length components of a box must add up to 4. I.e. the red + blue = 4

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In this question, i need help in last part
they have given domain so I thought that to get the range I just have to put 0 and 5 in the g(x)
and I got a range of g(x) any value less than or equal to 0 and 10 but the correst answer is
any value less than or equal to -2.25 and 10


It's a +ve quadratic. Clearly, it has a minimum point at x=32x=\frac{3}{2}. What is the function's value at this point? Hence since it's the MINIMUM value, the range is...?
Reply 5
Avatar for Qer
Qer
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Capture.PNG

still not understand ....there is 2 triangle
Original post by Qer


still not understand ....there is 2 triangle


Yes there is... and that's not the diagram I drew but if you want to work with yours - fine.

The length of the red line should be obvious in terms of θ\theta.
Then you want to find the vertical blue line's length in terms of θ\theta.

Convince yourself that the black angle's I've marked are actually θ\theta, then proceed from there.

Reply 7
Avatar for timif2
timif2
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4727FA6E-3837-4989-BF88-D2E06BD7C02B.jpg.jpegC9DD0540-FA21-44C1-9398-6ECAE2A7AD16.jpg.jpeg

Took me a while but there u go use what ur given
Reply 8
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Qer
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Original post by timif2
4727FA6E-3837-4989-BF88-D2E06BD7C02B.jpg.jpegC9DD0540-FA21-44C1-9398-6ECAE2A7AD16.jpg.jpeg

Took me a while but there u go use what ur given


thanks a lot, It also took me a while to understand what is going on by your working

just one question we know the position of theta in one triangle how you know where is theta in 2nd question or you just use the fact they mentioned that in question
Reply 9
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timif2
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Original post by Qer
thanks a lot, It also took me a while to understand what is going on by your working

just one question we know the position of theta in one triangle how you know where is theta in 2nd question or you just use the fact they mentioned that in question


For the first part, l1 and l2 are parallel, so the angle is an alternate angle, and equal

Or you can use alternate segment theorem, which is slightly more complex, but still works

For the second part, I just used the diagram :smile:

For question like these I just always try to use the information I’m given and I know, then break them down to see what we’re trying to find. Good luck
(edited 6 years ago)

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