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    y= sinx
    At 60° sinx =?3/2
    The sinx graph is 0<x? 360°
    What it is sinx at 120° and 180°?
    2 marks

    This is a GSCE transformation of curve question I think s? _ we haven’t done the topic yet. It was in my mock paper last week and I wanted to find out if what I wrote might be right: at 120° sinx =?6/2 and at 270° sinx=?12/2I wrote.
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    Do you know how to draw a graph of y=\sin x?

    If you do (as you need to), draw lines along x= \dfrac{\sqrt{3}}{2} and see what you notice where x=120,180.

    (Original post by Sunday=)
    if what I wrote might be right: at 120° sinx =(?6)/2 and at 270° sinx=(?12)/2, I wrote.
    That's not right I'm afraid.
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    (Original post by nuodai)
    Do you know how to draw a graph of y=\sin x?
    That's not right I'm afraid.
    I did not know how to draw the graph but I don't suppose you could also answer this question as well. It's a simitalneous equation:
    x^2+y^2=5
    y=3y+1

    when I worked it out x was -1 and and -0.4 and y was -2 and -1
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    (Original post by Sunday=)
    I did not know how to draw the graph but I don't suppose you could also answer this question as well. It's a simitalneous equation:
    x^2+y^2=5
    y=3y+1

    when I worked it out x was -1 and and -0.4 and y was -2 and -1
    Did you write it down correctly the equation?
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    sin120=rt3/2 as the sinx graph has reflectional symmetry along the lines
    x=90 (mod 180) (this just means it has reflectional symmetry along lines where x is 90 more than a multiple of 180 eg x=90, x=270, x=-90 etc). In this case we look at the line x=90. As 60 and 120 are both the same 'distance' from 90, their sine values will be the same.
    sin180=0, as does the sine of any multiple of 180 including 0 and negative multiples.

    I assume you meant to write y=3x+1 for the second equation.
    If so your answers are not quite correct. Also, you should write them in pairs of x,y:
    x=-1, y=-2 or x=2/5, y=11/5

    This means there will be no confusion as to which value of one variable implies which valuable of the other variable.
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    (Original post by hazbaz)
    Did you write it down correctly the equation?
    Yeah I see what you mean. They is a mistake, it's:

    x squared + y squared = 5
    y=3x+1

    Is this clearer?
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    (Original post by j.alexanderh)
    sin120=rt3/2 as the sinx graph has reflectional symmetry along the lines
    x=90 (mod 180) (this just means it has reflectional symmetry along lines where x is 90 more than a multiple of 180 eg x=90, x=270, x=-90 etc). In this case we look at the line x=90. As 60 and 120 are both the same 'distance' from 90, their sine values will be the same.
    sin180=0, as does the sine of any multiple of 180 including 0 and negative multiples.

    That silmitenous equation question was worth 6 marks, it was the last question on the paper too which means it must have been A*- how disapointing!

    And thanks for the transformation of curve info, you make it sound so easy but I'm no wiser.
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    (Original post by Sunday=)
    That silmitenous equation question was worth 6 marks, it was the last question on the paper too which means it must have been A*- how disapointing!

    And thanks for the transformation of curve info, you make it sound so easy but I'm no wiser.
    Sine graph: This has nothing to do with transformation of curves.

    Google image the sine graph. You will see that it is symmetrical along the line x=90. As 60 and 120 are the same 'distance' from 90 (both 30 away) their sine values will be the same. This will be made far clearer by looking at a good graph.
 
 
 
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