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  1. Q

    Addition formulae

    Sorry, I'm down to 'Cos²A + Sin²A(Cos²B - Sin²B)'. I don't know what you mean by add Sin²(A+B)
  2. Q

    cosx=10/x

    Okay, thank you. I did graph them, but this is what I get: It doesn't cross 3 times between the points...
  3. Q

    Period of a Graph

    Okay yeah, I thought the answer was 180. How do I go about the maximum value question?
  4. Q

    cosx=10/x

    Draw a sketch of Determine the number of roots of the equation which lie in the interval -180<x<180. I have no clue how to sketch this one, but it says the answer is 3.
  5. Q

    Period of a Graph

    Write down the period of the graph of and also the coordinates of a maximum value of y. So, I thought the period was 360 or 2Pi divided by the angle, but I'm not sure what to do here.
  6. Q

    CosXTanX Multiple Equation

    lol, sorry. thank you
  7. Q

    Addition formulae

    sorry, that's what I meant. so I'm still left with the negative
  8. Q

    CosXTanX Multiple Equation

    between -180 <X< 180 cosXtanX = -1/2 How the fudge do I solve this one? Obviously by reducing to one sign, but how? Tan = sin/cos is all I can think of, but that doesn't help. Please help.
  9. Q

    Addition formulae

    But cos²(A+B) = cosAcosB - sinAsinB, right?
  10. Q

    Addition formulae

    Use the addition formulae to find an expression for cos²(A+B)+sin²(A+B). Verify that your expression reduces to 1. Use a similar method to find an expression for cos²(A+B)-sin²(A+B). Verify that this reduces to cos(2A + 2B) So I get the the stage: cos²A(cos²B + sin²B) + sin²A(-sin²B + cos²B)...
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