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VCE Methods Question Thread!
Dominatorrr:
--- Quote from: dc302 on December 16, 2011, 06:02:12 pm ---
--- Quote from: Dominatorrr on December 16, 2011, 05:56:22 pm ---
--- Quote from: dc302 on December 16, 2011, 11:36:49 am ---To dilate by factor of 2 from y-axis means you need to replace x with x/2. This should give you the answer.
--- End quote ---
Yeah I think it makes sense now.
y=(4167/x^2)-1.67
y=(4167/0.5x*0.5x)-1.67
y=(4167/0.25x^2)-1.67
y=(16668/x^2)-1.67 (CLOSE ENOUGH)
--- End quote ---
Yep, and the reason your answer was a little off is because you rounded 12500/3 up to 4167, when it should be 4166.6(recurring)
--- End quote ---
Oh I see now, cheers
Dominatorrr:
"A light will reflect from a surface. Similarly, a function's negative portion will reflect in the x-axis when the modulus is taken. A ray of light originates from a position of (4,8) and hits the surface at an angle of 71.6 degrees."
(a) Find the equation of the light ray
I'm not sure how to use the angle to figure out the gradient?
TrueTears:
If an angle, theta, is made with the positive x axis, then tan(theta) is the gradient (why?)
Dominatorrr:
Ah yes that rule, I remember now, thanks.
Yet even then, my answer doesn't correspond to that of the book which is |3x-4|
I did 90-71.6=18.4
m=tan(theta)
m=tan(18.4)=0.33
y-y1=m(x-x1)
y-8=0.33(x-4)
y-8=0.33x-1.33
y=|0.33x+6.67|
TrueTears:
nah it's just tan(71.6) which is approximately 3, 71.6 is already the angle made with the positive x axis
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